I read somewhere that the glue they used was mucilage (like LePages) glue. Pretty sure that stuff is long gone, but there might be a substitute. I have a Little duke that had similar strip issues and used gorilla glue with a cue tip, which worked well for the loose paper.
The former owner used a few pieces of cellophane tape to hold them together, so there are a few lines where the dried-up tape was, but managed to keep the strips somewhat workable - and all original.
Slowly building a knowledge base on E2000 series Bally machines and J400 Jennings. Started with the antique Mills and Jennings. Getting there...