OK, so maybe it's just me. I was finally getting to the point where I was installing the balance in my Model 21 chronometer. Then, in with the screws for the HS stud, I found a silver colored bushing (spacer). I thought, hmmm..., where does this go? In the screw recess in the balance cock? No. Hmm...I guess I'd better check the parts list. So far I don't see it anywhere. At first I thought it might be the fusee or barrel bushing, but the realized that those were the brass bushings in the upper plate. Can someone give me a clue on where it goes? It fits well inside the balance-cock screw recess, as if it was a spacer, but the screw doesn't seem to pass through all the way, and it would probably cause the screw head to sit too high. Hints? Answers? Help? Thanks.