One of the original Campy rings on my Team Champion was starting to split before I purchased the bike, so I had to ask for a new one! (The dealer was reluctant to give me a new part but did.) Of course, I bought the bike new in Jan. '79 and it was a '77 model so had been sitting around the shop for a while.
The point is that even the Campy o-rings deteriorate over time.
Dan Wyman