The first failure mode for these headlight actuator motors is the OEM hard gel bushings. They act like a fuse in an electrical circuit and crack and crumble into chunks eventually causing the headlight motors to act erratically and ultimately not function to properly raise or lower the headlight doors at all. Once you have replaced these hard gel bushings with the Delrin bushings I manufacture they will be restored to their proper function. Now that we have identified and solved the first failure mode of these headlight actuator motors, what is the second failure mode? 

I pondered this question for many years. Will the next failure mode be the OEM cast nylon gear or something else? It was not until a local customer arrived to have his headlight motors repaired that I discovered the answer. The headlight motors had the classic symptoms of failed bushings. They would not rise when the headlight switch was pressed. I opened the motors to discover to my surprise that inside the motors were my Delrin bushings. What? "Oh Lon, don't you remember about 7 years ago you repaired them with your headlight repair kit?" I must confess I've repaired a lot of headlight motors for local customers, so no I did not recall having already replaced his failed bushings.

OK, now what the heck is going on? I cleaned the gear with WD40, blew it off with compressed air and inspected it. The gear was undamaged. Next I reassembled the headlight actuator and continued investigating. The headlight motor would turn the shaft as it should UNTIL I put a load on the shaft. I held the two flats on the shaft (that the lever arm fits onto) with an adjustable wrench. Then I turned the acorn knob on the top of the motor. It was then that I found the problem. The cast zinc 3-lobe shaft that is pressed onto the steel shaft that connects to the lever arm had broken free and was spinning. 

In this case I replaced the 3-lobe hub/shaft with a used one from another motor I had on-hand. Since my original discovery of this problem I have had a second customer's car with the same problem.

If your headlight actuator exhibit the symptoms of failing to raise or lower properly, open your headlight actuator motor. If the OEM bushings have been replaced and the gear is also found to be good, then you should test that the hub and shaft interface is intact as I've described previously.