What is the reason for being able to shift gears when the engine is off but not when it's running?

[DeNevaeh]

The reasons for being able to shift gears when the engine is off but not when it's running are as follows: 1. Reason: The clutch cannot fully disengage, while the gearshift mechanism of the transmission is functioning normally. Solution: This issue can be resolved by adjusting the clutch or replacing certain clutch components to ensure the clutch has appropriate free play and disengagement clearance. 2. Reason: The positioning components of the gear lever's positioning ball joint have failed, allowing the gear lever to rotate freely around its own axis, making it impossible to accurately control the gear position; alternatively, the spherical working surface at the lower end of the gear lever may have worn out, preventing the gear lever from controlling the shift fork or the shift head's groove, making both gear engagement and disengagement impossible. Solution: For the former, the issue can be resolved through repair; for the latter, the gear lever must be replaced.