Verify that the drive motor is turning when in motion, you need 2 people to check
If the motor is not turning, drain the oil out of the drive motor by removing the plug on the final drive motor
If you find metal in the oil, your planetary gears have been chewed up and will need to be repaired and checked for damage
If you find nothing in the oil, replace the gear oil 80/90w
Seals inside the motor maybe blown but before assuming that I would next remove the track and see if the motor turns when in motion step 1
If the motor turns it maybe a bad sprocket or track followed by possible bad roller or idler
If none of the above solves the issue you'll have to start checking electrical issues if the valve is controlled electronically followed by pressure testing
The above is based on a regular person that does not have mechanical background or proper testing equipment and or experience
Hope this helps
