All our old cameras need a little care occasionally, and many have foam seals that help keep them light-tight, but these deteriorate over time. For many years Jon Goodman has sold kits on ebay (under the seller name "Interslice"), but has recently had problems with some people copying all his good work and selling the kits and instructions as their own work. I believe Jon has suspended selling on ebay.
The good news is that he is still making kits, and selling direct! I recently contacted Jon for a kit for my "new" Fuji GSW690. Jon's kit just arrived in the post, and comes with all the foam strips required, plus a little tool to help remove the old foam, and a really comprehensive set of instructions that is specific to this camera. As a bonus, the instructions also cover removing the top cover and cleaning the viewfinder! I was planning to tackle that anyway so the instructions are very welcome.
If your camera needs seals, contact Jon at 'JGood21967@aol.com'.
Disclaimer: I have no connection to Jon, other than as a very satisfied customer.