Yes, BoxMann, my question was whether or not those odd symptoms may have been indicating an electrical problem beyond the motor/regulator. It occurred to me while I had it apart that the motor must be designed to reverse itself when it encounters resistance beyond a certain point, which happened once when I was testing the motor/regulator in the doo: the clamp that grabs the window hit something else on the way up and the motor reversed itself.
I took everything out of the door and took a good look. The problem may have been that the cable stretched out over the 22 years and developed some slack. I took apart the spool part of the regulator, driven directly by the motor. The two ends of the cable are wound around this yellow spool, one on the top (shown in the picture) and one on the bottom (out of sight). Both ends had bad kinks about an inch from the lead slug at the end of the cable, where the cable enters the spool- you can see it in the picture. I straightened those out and put everything back together. It still makes a tiny bit of noise but maybe about 10% of what it was.
I will order a replacement regulator for when it needs it, but I bought myself some time and can drive the car around till I get the part and can swap it out.
Cheers!
