Fid, I GOT IT!!!!!!!!!! These last pictures and description were spot on. My problem all along was the fact I could not get the medallion out of the horn ring. I guess 61 years of just sitting there had really sealed it in. So I soaked it in warm water for 30 minutes, and then gently pushed down along the inside edge with a sharp knife, and presto! It came out. The best part of all? The O-ring is in perfect condition, and I don't even need a new one. Now I just have to remove the plate, etc., and screw the horn ring to it and re-insert the medallion. As far as damage, I think everything is OK--miraculously. Thanks again.
