Same answer--ask the professionals who approach this kind of brittle collection on a regular basis. If you don't know how to do it yourself, leave it alone or you may crack it beyond repair. (But you've probably already figured that out, resourceful librarian that you are!)

There is a series of photo shops I think called Maisel that was recommended in the Seattle area for solving this kind of problem. That was years ago. I think there was one in Arizona also. Anyway, it's a name and I posted a link to the search.

SRS