the passenger electric seat isnt working properly. The back rest is fine, the seat tilt is fine, but it wont slide forwards or backwards.

I had a look under and when i try and move the seat, i can hear and see the motor trying to turn, but nothing. It just sort of clicks, and moves(twists on its fixings) slightly as if the output shaft is jammed.

Anyone know why it might be doing this and any solutions.