You can buy a kit to rebuild the headlight motors. The kit includes bushings, that tend to crumble over time, as well as new crankarms. The crankarms are made of a soft material that tends to wear out in the hole that fits on the shaft. The new crankarms are made of steel and will last the life of the car. I was thinking about rebuilding the headlight motors as preventive maintenance. If they have already been rebuilt you can check that off the list
Thanks to Barney Eaton for the photos.