David, most of these can easily be cleaned, sometimes, by a careful application of isoprophyl alcohol with a Q-tip. The key word is "careful" - at all costs avoid saturating the innards with alcohol as it may seep into the electronics and cause havoc when you eventually test it out with new batteries.
I salvaged a really beaut Nikon F65 bought for peanuts on Ebay with this technique. It also contained a roll of C41 but I've yet to process it - probably I won't, at my ripe old age my curiosity about other people's happy-crappy snaps has long vanished. The camera continues to work well, tho the lektrics are a bit wobbly and on occasion the camera has to be turned off and on again between shots, but it keeps on shooting and shooting.
I paid A$50 for this baby. Everyone I know insists that was way too much, but it came with a fplastic 28-80 Nikkor G zoom which I flogged off for A$5 less than the cost of the entire kit. So!
Give the alcohol and Q-tip treatment a try, you never know your luck. Not on the bellows on a folder, please. This from one who did, and knows.