My daughter's '86 GT with 87/88 Headlights had one light that would not open. When she cranked it up, it would slam down when she turned the headlights off. I posted a question about it and Ogre suggested the pot-metal part that engages the plastic gear via the the pins might be slipping on the output shaft. I took it apart yesterday and found that to be the case. My plan was to JB Weld the pot-metal part to the shaft but I could not get the pot-metal part off of the shaft (at least with the amount I was willing to pull on the pot-metal part with my gear puller). I looked in my toolbox and found a 1/8 X 3/4 roll pin. I drilled a #30 hole through one of the lobes of the pot-metal part and through the shaft. I drove the roll pin in sub-flush with the lobe of the pot-metal part and put everything back together. As of today, the headlight has gone through 15 open-close cycles and is working flawlessly.

With a drill press, this was an easy job and, hopefully, saves my daughter the expense of buying a new or rebuilt headlight motor.

Try Loctite Green formula too... Green wicks in the space after part are attached. Goes in shaft to metal part area.
Not sure if Green likes oil or not... But cleaning could be a problem. Maybe soaking in brake cleaner and dry w/ hair drier....

Also, That part failed can be a symptom of failing module. If module is goes south then you will have more problems. Not an easy way to tell if module is iffy, maybe one test that I know of...

check if motor power is cut at end of travel or motor has power for 5-6 seconds...
5 seconds mean module can see the motors load and module itself is bad.

See cave, Gen 2 HL motor in lighting section.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Thanks for the heads-up on the module. So far, the motor seems to stop as soon as the mechanism reaches the end of its travel.
Occasionally, there is a pause mid-travel going down but a light touch on the headlight switch gets it moving again.

I know about that pause. Dis-assemble the light switch and re-bend one of the tabs to fix that. It's just a tired copper contact.

Thanks, Gall.
I thought that would probably be the fix. Just doesn't bug me that much - being that it's my daughter's car and I never drive it. HaHa
If it were my 88 Formula, I would have taken care of it long ago.