I spent the last four days (well not all day, but enough to get frustrated 4 days in a row) trying to figure out why the power window in my '63 Rivi project suddenly quit working in the passenger door. I had juice to the switch, tried to take it apart to clean the contacts, it broke. Bought a new (to me) one, still didn't work. Finally occurred to me that, after much head scratching, that the door itself wasn't grounded to the body. I'd replace the motor because it was seized, worked fine after that. Then, I'd discovered that all but two of the eight door hinge mount bolts had been broken off. I drilled the bolts out of the cowl, tapped and replaced 'em all, and liberally lubed, WD40'd everything. Ah-HA! Why it didn't ground through latch is a mystery, but it didn't. After I figured out what the deal was, rather than take the door back off to clean and de-grease every bolt hole (it's a bitch to align these HEAVY doors), I ran a ground wire from the door skin to the cowl. What a pain, but a good example of how a poor ground can make the simplest thing seem complicated.