Here are the steps to replace a broken or worn X-axis GT2 belt
To complete this, you will need a phillips head screw driver, a 3mm allen wrench, and 47" of GT2 belt.
First you will need to remove the LED cover and BLTouch. This will give you access to the extruder mounting screws.
Next you will need to remove the extruder. It is held in place with 3 mounting screws. Once you have removed the extruder, simply let it sit on the print bed behind the X-axis arm.
With the extruder out of the way, you can now remove the GT2 belt. You will need to loosen the 4 screws used to clamp the belt to the X-axis carriage. Once the screws are loose, you will be able to remove the belt from your gMax. And you are now ready to start installing the new GT2 belt.
Before trying to insert the GT2 belt into the right side pulley, curl the belt in your fingers to help it curve around the pulley.
Keep pulling the GT2 belt along the X-axis rail. Make sure have the belt go behind the X-axis carriage.
If you are not able to curl the GT2 belt around motor drive gear, you may have to remove it from the X-axis arm. Once the GT2 belt is around the X-axis drive gear, remount the motor to the X-axis arm.
Now you will clamp the belt back onto the X-axis carriage. Start with the right clamp. Make sure to keep the belt flush with the inside edge of the clamp and tighten the screws to secure the belt. You should have 1-2 inches of extra belt after it is inserted into the left side clamp. Hold onto the excess belt while pushing the X-axis carriage to the left with your finger. This will give tension to the GT2 belt. The tighten the remaining belt clamp screws.
You can now reattach the extruder to the X-axis carriage and reinstall the BLTouch and LED cover.
Once this is complete, you will have to run bed leveling again as well as dial in your BLTouch. If you have a dual extruder, you will need to level your extruder as well.