isolate the power first, then check as to whether the motor turns freely,.
Try turning it by hand,
its possible you have fitted the brushes incorrectly,that's not to say you have,but I have seen it many times.
now either the motor has failed, the taco or start capacitor (if fitted ) has failed,or the motor isn't getting the power/voltage to run it.
If you have a multimeter you can selact a cycle and meter the motors wiring connector,
if you have voltage then the motor has faild,
if you have no voltage then back track through the motors wiring, door interlock pcb/program module,
paul, March 2012
