since it is so hard to find a blade for the '82 arm i thought i would put a junkyard '87 assembly in the '82. Everything fits perfectly, motor runs and parks on the bench but will not work in the car. There is ignition power to the grey wire and when touched to the grey wire on the motor it tries to run backwards about 3 degrees then stops. if i run it a few degrees and apply ignition power to the park wire it tries to park a few degrees but backwards. cannot figure out what is going wrong.