Today I replaced the spur gear and motor for the driver's side folding mirror. Being cheap I opted not to just buy the housing already rebuilt so there's a bit of fiddling to crack open the housing and install the motor and gear, but it was well worth the $160 savings. The old plastic gear had a slick ring all of the way around the center of it and the motor wouldn't spin it anymore.
I did a search and found this thread:
https://www.tahoeyukonforum.com/threads/found-a-fix-for-broken-power-fold-mirrors.92358/
This gave me the supplier:
Welcome to Gruven Parts, your online home for custom auto parts.
www.gruvenparts.com
And his instructions:
www.gruvenparts.com
I just took my time removing the gear and motor from the casing and since I don't have a vise or arbor press I improvised but didn't put my eye out.
I couldn't get the puddle lamp connector to come off but just removing the bulb, connector and all worked fine.