I have an old Raleigh 531 frame that I had the fork replaced on when it was almost new (misaligned dropouts). The shop I bought the frame from didn't have a seat cutter (the seat was bigger than my campy race), so I took it to a machine shop, who cut the seat too small. I've always used a piece or two of shim stock in with the race and it has worked fine all these years. I would like to fix it correctly however, so am asking if this is something that could be done? Does in involve replacing the crown lug or are there other ways of dealing with this? Thanks.