Enlarger in need of treatment

This week I was very surprised to receive as a gift an enlarger, a Meopta Opemus 2A, which I sold more than 30 years ago, and bought new 40, maybe 50, years ago. During all the years since I sold it, it was never used, so I even got my old chemicals, papers etcetera in return. Unfortunately, the last few years it had been kept in an unheated space, so there are some things to do in order to get it in ”perfect” shape again. Among others, the bellows are so stiff that I don’t dare to try to press them together. Furthermore, there is a leakage in one of the bellows' folds.
My questions:
What are the bellows made of? Is there a way to make the bellows soft again? How do I seal the leakage? Are new bellows or something that can replace them available?

If you can't repair the old bellows, a cheap stop gap solution might be to get some light blocking cloth (blackout cloth, darkroom cloth, etc) and make sort of a "bag bellows" that wraps around and just loosely sits over the old bellows to provide complete dark protection. You could attach it to the negative stage and lens stage, and the old bellows , even if it leaks or cracks, would just act as a scaffold to keep it out of the light path.

Otherwise you can fold a new bellows or buy a replacement somewhere maybe.

Thanks to walter23 for your interest and suggestions.

I have talked to two old hands at two different camera repair shops. Both told me that they use heavy grease in order to make old camera bellows supple again. I have something called Leather milk for furniture, probably just diluted grease, and have applied it to the bellows by brush. My bellows are so dry and stiff that a little extra moisture won't hurt. Olny a few hours later they could be flexed somewhat. Then I applied leather grease, which I use to make shoes water repellent. The grease has started to go into the bellows, and they already flex like new. I shall finish off the work by applying shoe polish just to make them look like new (after that they shall go back into the darkroom, where nobody sees how beautiful they look -
I shall try to fix the light leakage by electrical tape on both sides.

Dennis