Hiya Heather,
I'll put a few links to the posts I've done in the past on this subject.
There are more here from others also so surf the posts here in the forums.
I hope they help some.
http://www.rubberslug.com/board/showthread.asp?T=1142
http://www.rubberslug.com/board/showthread.asp?T=1030
http://www.rubberslug.com/board/showthread.asp?T=1092
http://www.rubberslug.com/board/showthread.asp?T=919
http://www.rubberslug.com/board/showthread.asp?T=545
There are a few more posts here If you can't find what your looking for let me know and I'll see if I can find it in one of my books or links I have.
I have seen some folks make a full size copy of there stuck cels and use photo shop to remove the eyes or mouth, To put the extra cels they have over it to see what set of eye/mouth they want to use on the hold cel to see what it looks like.
This way they don't mess there hold cel up or the eyes that are stuck to the hold cel.
There is alot of reading with all these posts above, But most stuck things and cel care are listed there, Read them all before you try any of them.
These ideas are just things I've seen that work, But if you are not sure, The best thing to do is to take the artwork to a art dealer and let them do it for you, But it will cost a bunch to get them to do it for you.
Thanks E for the post about me and I don't mind sharing what I've learned in the past, This is one way we can keep the knowledge going down the line to all the newbies and others needing info about cel collecting.
As all the old school animators are dying off we are losing all this type of knowledge and info we all need. So if you learn it pass it on down for the future collectors, they will need it also.
Once more I hope this helps some.
Roy