My attitude indicator in my RV-6A actually failed a few weeks ago for the second time in 410 hours. The first time was what I consider a legitimate failure from buying the instrument early to make up the instrument panel then leaving it set it the exact same positiong for years while I finished the plane and then flew it for a couple of hundred hours. This last one happened not too long after I had a vacuum pump failure with no blowback protection in-line filter between the pump and the instruments. I drove down to Rudy Arkansas on Friday afternoon and I was called on Monday to come pick it up. Mike at Rudy Aircraft Instruments told me that the rotor was badly contaminated with debries from the pump failure and he replaced the bearings, serviced, tested and certified the instrument.
I know from your posts that you are a very talented person and I have little doubt that you can accomplish the replacement of the bearings. It, no doubt would be a very educational exercise. Just one precaution, I do not think the repared instrument would be legal for instrument flight and it would probably at least require placarding against it but I'm not prepared to defend that position. Some talk about the FARs sounds as if they fit in one nice little book but that is not the case. During a short period as Manager of Systems Operations and System Support at Douglas Aircraft in Long Beach the Technical Library was one of the organizations I was responsible for. The FARs were a significant update responsibility for the two people working there and these not unambiguous documents occupied a very large section of the library.
Bob Axsom