I just searched your previous posts to where you said you had a 94 Bird (the year helps cause there are 4 motor styles from 82-92).
It sounds like it could be related to the nylon gear that drives the light up and down. A lot of problems and strange tempermental actions by the lights derive from a worn or stripped headlight gear. And by working on the assembly, couldn't have done something to the motor.
This is a great read if you got a few minutes.....
http://www.bfranker.badz28.com/headl...htgearfailures