One of the silent problems with these older cameras is hidden necessary repairs. Recently, I purchased a Nikon F2 which needed all the seals including the mirror slap foam replaced. I had replaced foam before and even had enough foam however I chose to send it off to have it done. What I was told that since the camera had been sitting for years the shutter was dirty and speeds were off; two things I had not discovered and would not have discovered (all the shutter speeds sounded different and everyone fired). Another issue is that sometimes the foam gets into other parts of a camera and a CLA is needed to remove it. The question to be asked is when do I replace the foam myself and when to have a professional do it? Depending upon your skill level if the camera is a Yashica GSN, for example, I would go ahead and do it as a repair would be more than the camera is worth. If it is an expensive or higher end model which you plan to use regularly I'd have someone else look at it. IMHO
Your other option was sending it back as not complaint with description... And buy the next eBay special.
Pro camera repairs are frequently worth more than the camera.
If your F2 shutter curtain material is damaged replacement is not economic instead buy another F2 body they are cheap.
If you notice foam deterioration replace immediately if you damage a film sprocket hole clean debris out immediately, shutters can react badly to foam or film shards.
I've seen a FM where the shutter looked like origami.
Replacing foam on GSN may not be meaningful as the PODs don't last long either... If you can replace the POD inspect it with foam...