Thanks for all the replies, now have a way forward.

Apologies if this has been asked before and it's a stupid question. I've just unpacked my RAM mint sets (Proof & UNC) from the back of the cupboard. I haven't opened or looked at these for about 30 years so I can only blame myself. I have approx 38 UNC sets in the PVC folders from 1975 to 2002 - at that point I gave up purchasing from the Mint. The later UNC sets seems OK, but the 1970s sets are covered it that PVC gunk. I've bought some acetone with the hope of recovering some of the coins.  

However is there anything I can do to recover the actual wallets? And are the UNC mint sets worth anything without the wallets?
Are the later wallets a different plastic and is it safe to keep the coins in them?