ST20 support

Identify the problem area

Identify the problem area
Identify the problem area
  1. 1 Blade
  2. 2 Hub
  3. 3 Shroud cover
  4. 4 Trimmer head & adjuster button
  5. 5 Main body
  6. 6 Handle
  7. 7 Safety button
  8. 8 Trigger
  9. 9 Removable battery with state-of-charge indicator

Troubleshooting

Check that the battery is charged

We know it sounds silly, but it’s always worth double checking that your battery is actually charged!

To charge the battery, remove it from the handle of the ST20 by squeezing the green buttons on the sides of the battery. Pull it away from the trimmer. Press the green button in the middle of the battery to show the state-of-charge display – if 1 green light is shown, you will need to charge your battery.

Plug the charger into the charging port on the end of the battery. 1 green light will appear on the state-of-charge display while it charges. 4 solid green lights will illuminate when the battery is fully charged after 4 hours. 

Check that the battery is fitted correctly

Remove the battery from the handle by squeezing the green buttons on the sides of the battery and pulling it away from the main body. Check the battery, terminals and housing for signs of damage.

Reinsert the battery into the end of the handle, ensuring the terminals line up. Push the battery inwards until you hear it click into place. 

Are you pressing the safety button?

Press and hold the safety button on one side of the handle while pressing the start trigger. Only one side of the safety button can be pressed at once, so don’t try to squeeze them both at the same time!

You can release the safety button once the trimmer has started, just continue to press the start trigger. The safety button should stay pressed in while you are pressing the trigger. If it pops out, the machine will cut out. 

Is the trigger pressed?

The trigger must be continuously pressed down. The machine will stop when the trigger is released. 

Is the blade jammed?

Remove the battery before carrying out any maintenance work.

If the blade is jammed, the machine will cut out. Remove the battery from the trimmer and remove the obstruction(s) from the blade. Refit the battery and retry.

If the blade has been damaged, replace the blade – you can buy replacement blades online via our spares page. 

Check that the head is correctly fitted

Remove the battery before carrying out any maintenance work.

The trimmer will not work if the trimmer head is not correctly fitted onto the main body. Remove the head by pressing in the black head-release button, which can be found on the handle. Pull the head away from the handle.

Refit the head, making sure both parts are the correct way up and the black button on the body clicks the head securely into place. 

The battery terminals or head terminals may be dirty or damaged

Remove the battery before carrying out any maintenance work.

If dirt or dust gets into contact with the battery or head terminals, they won’t connect properly. Remove the battery from the handle and use a dry, soft cloth to clean the terminals on the battery and battery-housing. Remove the head by pressing in the black head-release button, which can be found on the handle. Pull the head away from the handle.

Use a dry, soft cloth to clean the terminals inside the head of the trimmer - these look like 2 silver pins. Reattach the head, insert the battery and try again.

The type of grass you’re cutting will affect run-time

Run-time will be reduced depending upon the thickness/ length of grass being cut. Check that the height adjuster has been correctly selected for grass type and length. If you are cutting something thick, try doing it in stages rather than all at once if you’re struggling. Do not attempt to trim wet grass.

Check if the blade is worn or damaged

Remove the battery before carrying out any maintenance work.

Blades naturally wear down as they are used, we would recommend replacing the blade before every use or when it is worn or damaged. Lucky for you, you can easily order them through our spares page.

Your trimmer comes with a full manual, detailing how to assemble it correctly. Refer to your manual or download another version by clicking on the download button.

Check that the battery is charged

We know it sounds silly, but it’s always worth double checking that your battery is actually charged!

To charge the battery, remove it from the handle of the ST20 by squeezing the green buttons on the sides of the battery. Pull it away from the trimmer. Press the green button in the middle of the battery to show the state-of-charge display – if 1 green light is shown, you will need to charge your battery.

Plug the charger into the charging port on the end of the battery. 1 green light will appear on the state-of-charge display while it charges. 4 solid green lights will illuminate when the battery is fully charged after 4 hours. 

Check that the battery is fitted correctly

Remove the battery from the handle by squeezing the green buttons on the sides of the battery and pulling it away from the main body. Check the battery, terminals and housing for signs of damage.

Reinsert the battery into the end of the handle, ensuring the terminals line up. Push the battery inwards until you hear it click into place. 

The battery terminals may be dirty or damaged

Remove the battery before carrying out any maintenance work.

If dirt or dust gets into contact with the battery or head terminals, they won’t connect properly. Remove the battery from the handle and use a dry, soft cloth to clean the terminals on the battery and battery-housing. Insert the battery and try again. 

Check the battery lights

•1 solid green light flashes for 10 seconds

Charge the battery for 4 hours until all 4 lights on the state-of-charge display turn solid green.

•4 solid red lights while the trimmer is in use

The blade has jammed – Remove the battery from the trimmer and remove the obstruction(s) from the blade. Refit the battery and retry. If the blade has been damaged, replace the blade – you can buy replacement blades online via our spares page.

•4 solid red lights when the battery is detached from the trimmer

This suggests that the battery has been stored in extremely hot/ cold temperatures. Keep the battery somewhere at room temperature for 24 hours and then fully charge the battery for 4 hours.

•4 flashing red lights

The battery has overheated. Remove the battery from the trimmer (and from the charger) and allow the battery to cool for 10 minutes. Refit the battery and try using the trimmer again.

Check the charger

If you’ve worked your way through the above steps and your ST20 is still not working, it may be an issue with your charger. There are a few ways you can check if there’s an issue with the charger.

When the battery is put on the charging stand, a green light should illuminate on the stand and pulsating green lights should show on the battery while it charges. If there are no lights illuminated, continue to the next step.

If the battery is fitting loosely in the charging stand, there will be excessive movement when the battery is plugged in and it may not charge correctly. Get in touch with us as we may need to send you a replacement part.

Check to see if the charger gets warm when it is charging the battery. Check for signs of damage to the charger cable. If it’s ripped or frayed, or if the terminals pins are broken on the charger, you need a replacement charger to ensure your trimmer works safely. You can buy a replacement charger online via our spares page.

Check for signs of damage to the hole in the battery that the charger goes into. If you can’t see anything wrong with your charger but it’s still not working, try plugging it into another socket as it may be an issue with the mains.

If you have a spare charger, try using that one instead – the ST20 is compatible with the chargers for the AirRam/ K9, Multi/ K9, Pro/ K9, Power Floor/ K9, HT20 and Work Light.

If you’ve taken all the steps to check your battery and charger and your trimmer still isn’t charging, get in touch with us as we may need to send you a replacement part.

Is the blade fitted correctly?

Remove the battery before carrying out any maintenance work.

Remove the blade from the hub (rotating disc) and push the blade back so that the blade pin fits into the larger hole on the blade. Lift the blade off the blade pin and check for any signs of damage.

If there are no signs of damage, hook the blade over the blade pin located on the hub (rotating disc) and pull the blade forwards firmly so that the blade pin fits into the small hole to secure it into place.

If the blade is still not fitting correctly, check that the blade pin is not damaged or try using a new blade.

Ensure the hub is securely fitted in place by the hub screw - this should be tightened before every use. If the blade pin is loose, worn or damaged, get in touch with us as we may need to send you a replacement part.

The blade is not cutting

Remove the battery before carrying out any maintenance work.

Remove any obstruction(s) from around blade/ branch-cutter and retry the trimmer. Check the blade for signs of damage. If the blade is damaged or worn, replace it with a new blade - you can order replacement blades online via our spares page.  

The blade is not moving

Remove the battery before carrying out any maintenance work.

Check that the hub’s (rotating disc’s) screw and washer are tight enough to hold the hub in place. This screw should be tightened before every use. Tighten the screw and try using the trimmer again.

Trouble adjusting the handle

Press the green handle adjustment button and hold it down to adjust the handle to the required position. Only one side of the button will freely spring in/ out.

Release the button once you have positioned the handle as preferred. The handle will click and lock into place. 

Trouble pressing the handle adjustment button

Check that you’re using the correct side of the handle adjustment button - only one side of the button will freely spring in/ out. 

Trouble fitting the trimmer head

The black button located at the bottom of the main body should easily spring in and out when pressed. Line up the button with the small hole in the neck of the trimmer head.

When correctly fitted, the black button should pop through the hole in the trimmer head, locking the head and main body into place.

Trouble adjusting the angle of the trimmer head

Press only one side of the green angle adjustment button, located just below the neck of the head (only one will depress). Hold down the button to select the angle required and release it once you’ve chosen. The trimmer head will click and lock into place.

If the button won’t press in (remember that only one of them will depress, so make sure you’ve tried each one!), you can order a replacement trimmer head and shroud online via our spares page. 

Trouble removing the trimmer head

The head may be incorrectly fitted, making it hard to remove.

The black button located at the bottom of the main body should be pressed in. If it’s not, push it it and pull the main body and trimmer head apart to separate them.

If the black button has not locked into the main body, firmly pull the main body and trimmer head to separate.

The hub has detached from the trimmer head during use

The screw may not be tight enough to hold the hub in place. You can order a replacement trimmer screw and washer or, if the hub is damaged, you can order a replacement hub which will include a new screw and washer online via our spares page. 

The hub is damaged

The hub is a replaceable part and can be detached from the trimmer head by removing the cross-head screw with a screwdriver. You can order a replacement hub online via our spares page.

If the blade pin is damaged, you can order a replacement hub. If the screw is missing or damaged, you can order a replacement trimmer screw and washer online via our spares page. 

Troubleshooting

No Power

Check that the battery is charged

We know it sounds silly, but it’s always worth double checking that your battery is actually charged!

To charge the battery, remove it from the handle of the ST20 by squeezing the green buttons on the sides of the battery. Pull it away from the trimmer. Press the green button in the middle of the battery to show the state-of-charge display – if 1 green light is shown, you will need to charge your battery.

Plug the charger into the charging port on the end of the battery. 1 green light will appear on the state-of-charge display while it charges. 4 solid green lights will illuminate when the battery is fully charged after 4 hours. 

Check that the battery is fitted correctly

Remove the battery from the handle by squeezing the green buttons on the sides of the battery and pulling it away from the main body. Check the battery, terminals and housing for signs of damage.

Reinsert the battery into the end of the handle, ensuring the terminals line up. Push the battery inwards until you hear it click into place. 

Are you pressing the safety button?

Press and hold the safety button on one side of the handle while pressing the start trigger. Only one side of the safety button can be pressed at once, so don’t try to squeeze them both at the same time!

You can release the safety button once the trimmer has started, just continue to press the start trigger. The safety button should stay pressed in while you are pressing the trigger. If it pops out, the machine will cut out. 

Is the trigger pressed?

The trigger must be continuously pressed down. The machine will stop when the trigger is released. 

Is the blade jammed?

Remove the battery before carrying out any maintenance work.

If the blade is jammed, the machine will cut out. Remove the battery from the trimmer and remove the obstruction(s) from the blade. Refit the battery and retry.

If the blade has been damaged, replace the blade – you can buy replacement blades online via our spares page. 

Check that the head is correctly fitted

Remove the battery before carrying out any maintenance work.

The trimmer will not work if the trimmer head is not correctly fitted onto the main body. Remove the head by pressing in the black head-release button, which can be found on the handle. Pull the head away from the handle.

Refit the head, making sure both parts are the correct way up and the black button on the body clicks the head securely into place. 

The battery terminals or head terminals may be dirty or damaged

Remove the battery before carrying out any maintenance work.

If dirt or dust gets into contact with the battery or head terminals, they won’t connect properly. Remove the battery from the handle and use a dry, soft cloth to clean the terminals on the battery and battery-housing. Remove the head by pressing in the black head-release button, which can be found on the handle. Pull the head away from the handle.

Use a dry, soft cloth to clean the terminals inside the head of the trimmer - these look like 2 silver pins. Reattach the head, insert the battery and try again.

The type of grass you’re cutting will affect run-time

Run-time will be reduced depending upon the thickness/ length of grass being cut. Check that the height adjuster has been correctly selected for grass type and length. If you are cutting something thick, try doing it in stages rather than all at once if you’re struggling. Do not attempt to trim wet grass.

Check if the blade is worn or damaged

Remove the battery before carrying out any maintenance work.

Blades naturally wear down as they are used, we would recommend replacing the blade before every use or when it is worn or damaged. Lucky for you, you can easily order them through our spares page.

Your trimmer comes with a full manual, detailing how to assemble it correctly. Refer to your manual or download another version by clicking on the download button.

Battery & Charging

Check that the battery is charged

We know it sounds silly, but it’s always worth double checking that your battery is actually charged!

To charge the battery, remove it from the handle of the ST20 by squeezing the green buttons on the sides of the battery. Pull it away from the trimmer. Press the green button in the middle of the battery to show the state-of-charge display – if 1 green light is shown, you will need to charge your battery.

Plug the charger into the charging port on the end of the battery. 1 green light will appear on the state-of-charge display while it charges. 4 solid green lights will illuminate when the battery is fully charged after 4 hours. 

Check that the battery is fitted correctly

Remove the battery from the handle by squeezing the green buttons on the sides of the battery and pulling it away from the main body. Check the battery, terminals and housing for signs of damage.

Reinsert the battery into the end of the handle, ensuring the terminals line up. Push the battery inwards until you hear it click into place. 

The battery terminals may be dirty or damaged

Remove the battery before carrying out any maintenance work.

If dirt or dust gets into contact with the battery or head terminals, they won’t connect properly. Remove the battery from the handle and use a dry, soft cloth to clean the terminals on the battery and battery-housing. Insert the battery and try again. 

Check the battery lights

•1 solid green light flashes for 10 seconds

Charge the battery for 4 hours until all 4 lights on the state-of-charge display turn solid green.

•4 solid red lights while the trimmer is in use

The blade has jammed – Remove the battery from the trimmer and remove the obstruction(s) from the blade. Refit the battery and retry. If the blade has been damaged, replace the blade – you can buy replacement blades online via our spares page.

•4 solid red lights when the battery is detached from the trimmer

This suggests that the battery has been stored in extremely hot/ cold temperatures. Keep the battery somewhere at room temperature for 24 hours and then fully charge the battery for 4 hours.

•4 flashing red lights

The battery has overheated. Remove the battery from the trimmer (and from the charger) and allow the battery to cool for 10 minutes. Refit the battery and try using the trimmer again.

Check the charger

If you’ve worked your way through the above steps and your ST20 is still not working, it may be an issue with your charger. There are a few ways you can check if there’s an issue with the charger.

When the battery is put on the charging stand, a green light should illuminate on the stand and pulsating green lights should show on the battery while it charges. If there are no lights illuminated, continue to the next step.

If the battery is fitting loosely in the charging stand, there will be excessive movement when the battery is plugged in and it may not charge correctly. Get in touch with us as we may need to send you a replacement part.

Check to see if the charger gets warm when it is charging the battery. Check for signs of damage to the charger cable. If it’s ripped or frayed, or if the terminals pins are broken on the charger, you need a replacement charger to ensure your trimmer works safely. You can buy a replacement charger online via our spares page.

Check for signs of damage to the hole in the battery that the charger goes into. If you can’t see anything wrong with your charger but it’s still not working, try plugging it into another socket as it may be an issue with the mains.

If you have a spare charger, try using that one instead – the ST20 is compatible with the chargers for the AirRam/ K9, Multi/ K9, Pro/ K9, Power Floor/ K9, HT20 and Work Light.

If you’ve taken all the steps to check your battery and charger and your trimmer still isn’t charging, get in touch with us as we may need to send you a replacement part.

Blade Not Cutting

Is the blade fitted correctly?

Remove the battery before carrying out any maintenance work.

Remove the blade from the hub (rotating disc) and push the blade back so that the blade pin fits into the larger hole on the blade. Lift the blade off the blade pin and check for any signs of damage.

If there are no signs of damage, hook the blade over the blade pin located on the hub (rotating disc) and pull the blade forwards firmly so that the blade pin fits into the small hole to secure it into place.

If the blade is still not fitting correctly, check that the blade pin is not damaged or try using a new blade.

Ensure the hub is securely fitted in place by the hub screw - this should be tightened before every use. If the blade pin is loose, worn or damaged, get in touch with us as we may need to send you a replacement part.

The blade is not cutting

Remove the battery before carrying out any maintenance work.

Remove any obstruction(s) from around blade/ branch-cutter and retry the trimmer. Check the blade for signs of damage. If the blade is damaged or worn, replace it with a new blade - you can order replacement blades online via our spares page.  

The blade is not moving

Remove the battery before carrying out any maintenance work.

Check that the hub’s (rotating disc’s) screw and washer are tight enough to hold the hub in place. This screw should be tightened before every use. Tighten the screw and try using the trimmer again.

Handle

Trouble adjusting the handle

Press the green handle adjustment button and hold it down to adjust the handle to the required position. Only one side of the button will freely spring in/ out.

Release the button once you have positioned the handle as preferred. The handle will click and lock into place. 

Trouble pressing the handle adjustment button

Check that you’re using the correct side of the handle adjustment button - only one side of the button will freely spring in/ out. 

Trimmer Head

Trouble fitting the trimmer head

The black button located at the bottom of the main body should easily spring in and out when pressed. Line up the button with the small hole in the neck of the trimmer head.

When correctly fitted, the black button should pop through the hole in the trimmer head, locking the head and main body into place.

Trouble adjusting the angle of the trimmer head

Press only one side of the green angle adjustment button, located just below the neck of the head (only one will depress). Hold down the button to select the angle required and release it once you’ve chosen. The trimmer head will click and lock into place.

If the button won’t press in (remember that only one of them will depress, so make sure you’ve tried each one!), you can order a replacement trimmer head and shroud online via our spares page. 

Trouble removing the trimmer head

The head may be incorrectly fitted, making it hard to remove.

The black button located at the bottom of the main body should be pressed in. If it’s not, push it it and pull the main body and trimmer head apart to separate them.

If the black button has not locked into the main body, firmly pull the main body and trimmer head to separate.

Rotating Disc (Hub)

The hub has detached from the trimmer head during use

The screw may not be tight enough to hold the hub in place. You can order a replacement trimmer screw and washer or, if the hub is damaged, you can order a replacement hub which will include a new screw and washer online via our spares page. 

The hub is damaged

The hub is a replaceable part and can be detached from the trimmer head by removing the cross-head screw with a screwdriver. You can order a replacement hub online via our spares page.

If the blade pin is damaged, you can order a replacement hub. If the screw is missing or damaged, you can order a replacement trimmer screw and washer online via our spares page. 

Download Manual

Download manual

For more information on how to set up your product, download the manual.

Download
Register your product

Register your product

Register

Register to access your Gtech warranty, and for quicker and more efficient support tailored for you.

Support videos

Still need a hand?

We're ready when you are

Let's chat

Need help now? Open up our live chat and get typing

Drop us a line

Not got time now? Contact us via email.

Email
Talk to our support team

Our friendly Customer Service Agents are on-hand to help.

0800 484 0215

Monday-Friday
8am-8pm
Saturday-Sunday
9am-5:30pm