Old Glue Rejuvenation Question

[JollyElm]

Okay, this is a bit out of left field (pun intended), but I'm wondering if anyone has some insight into a semi-hypothetical situation. I'm looking to restore something on my own, and want it to be as close to its original state as possible. (I guess I should state that it's something for my PC, and not something I'm looking to sell, so it isn't an attempt to do anything shady.)

Say you have a very old scrapbook type of thing that has cards and pictures glued into it. The glue is obviously not water-soluble. It's the immovable, hard-dried stuff of yesteryear.

Here's my question: If some of the cards have become (not fully) detached from the cardboard-esque pages, is there a way to somehow rejuvenate at least a bit of the glue on back to make it liquified again, so I can re-attach everything? Sure, I could easily just put a drop of Krazy glue on the back and reattach each piece, but I really want it to be glued by the original glue itself.

I know I can try applying heat to see if it melts a bit, but that would put the pieces and the album itself in burn jeopardy, something I want to avoid. I will certainly try it to see if it'll work, but are there any other suggestions? Chemicals are fine if they rejuvenate the glue and make it sticky again. I wouldn't have a problem with that.

Bottom line, other than intense heat, is there a way to get serious old-time glue acting like it's 1930 and it's still in the paste bucket??