I can't mount bearings. My back wheel was wobbling so I took apart the hub to clean, re-lube, and tighten the bearings. But the balls weren't in cages, and I couldn't get them back in. Off to the LBS (who didn't laugh at me, at least not while I was there) and they showed me brinelling on the bearing race, the cause of the wobbling. So it needed to be replaced anyway. But I'm not opening my bottom bracket for fear of losing more bearing balls.
#BikeNite A4