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