How to remove old glue in model making without causing damage?

Good bye ,

My father once gave me a signal box, which I've now dug out again after he found his model railway stuff. The whole thing also started a small flame, and I wanted to spruce up my signal box a bit.

My question is, how do I remove the adhesive from the segments without causing any damage, or even remove the segments altogether, which would make conversion easier.

No, I didn't rip the roof off, that was my father because he wanted to bring light into the darkness with SMD LEDs.

Kind regards