Rocketeer

Hey leonf, thanks! You're right -- I left the rock shaft et al. in place. After I had done everything else, I just got a little too nervous about putting all those shafts back in place and recalibrating them, though I did manage to adjust the feed dog height. There's a lot of eccentric things down there.
As for the bearing, I used MRC 37FF (https://www.motionindustries.com/pro...p?sku=00039888) that I bought from my "bearing guy" Jon -- one of the many folks I've made lovely connections with surrounding the need for parts or tools for this project. Replacing it was harrowing. I had to pound the shaft down through the old bearing until it popped out, remove the bearing from the silver aluminum half of the motor housing, press the new bearing back into that housing with the aid of washers that matched the size of the outer race, and then -- this is the craziest part -- locate sections of metal cuffing that were wide enough to fit snugly around the shaft but small enough only to contact the *inner* race, so I wouldn't stress the bearing by applying opposing pressure to the two races. I found the stuff at Bolt Depot, one of my favorite suppliers. You can see two of the metal collars taped together in the pipe clamps photo. I had to have them in sections so I could press the bearing onto the shaft in increments.
Actually I didn't *have* to do any of this -- the old bearing was spinning nicely and I suspect that even though they're not supposed to be re-lubricated, the fact that it's only piloting the shaft rather than actually bearing any weight means a little re-lubrication would have worked fine. But I'm sometimes a perfectionist and wanted to feel that my 500A was the best it could be. I also love a mechanical challenge!