Originally posted by boriscleto But most of the cameras are much older...
It is my experience that seals may go bad in as little as eight years. Much depends on the amount of ozone in the air and the quality of the last set of seals installed. My Super Program (no older than 1984) required new seals when I bought it three years ago and my Olympus XA (no older than 1979) has had two sets of seals since I bought it eight years ago.
It is a good rule of thumb to inquire about the state of the seals before purchase and then test the seals immediately upon receipt. Do it even before testing the shutter since goo from disintegrating mirror bumper foam can be flung onto the mirror and focus screen where it is difficult to remove.
To test, use a wooden toothpick to touch the seal and mirror bumper material. It should be springy and should not be sticky or crumbly.
Seal replacement is fairly easy to do and not expensive. For example, it took me less than 1/2 hour to install one of Jon Goodman's excellent kits in my Minolta SRT 101 a few months back. Seal replacement is included in a CLA.
Steve