Power Mirror Rebuild Parts?

I think I asked this a long time ago, but has anyone come across rebuild parts for the power mirror assemblies?

I know you can buy entire units for $100 each, but my original mirrors are in excellent shape with great glass, but squeal and don't go up/down anymore (but can hear motor)

I'd prefer to rebuild them, but short or trying to find some good used mirrors and swapped parts over, I haven't seen much out there.

Will be a winter project of mine to pull them apart and see what exactly is the issue

Not yet. Pretty easy to pull them off though. More or less something to do when it's 5 degrees outside and I'm sick of house projects.

The motors whirr, but loudly. Wonder if I could lubricate them up.