I recently had a minor issue with my Yashica 635. The plastic "window" that covers the aperture and shutter speed scale fell out, and found its way down inside the front fascia of the camera, into the aperture coupling mechanism. This promptly jammed at f/22. I took the front of the camera apart to see if I could fix it; the plastic window was hung up between a gear and a piece of brass "foil" that were both part of the coupling between the dial on the camera and the aperture ring on the lens. So... even though I was able to remove the window from the works, the mechanism didn't work anymore. I suppose I need a replacement for the piece of brass that got bent. The lens aperture itself works fine. I was very sad, thinking that I would have to stop using this camera; it was my mother's when she studied photography fifty years ago, and has been with me for my entire twenty-plus year photographic journey.
Then I realized that all is not lost. After all, the only thing the camera no longer has is a taking lens/shutter. There is still a perfectly light-tight box with a film transport for either 35mm or 120 film, as well as a very nice viewfinder.
And then there is a perfectly usable 80mm lens in a working shutter, complete with a retaining ring. Hmmm.
So the results of this little adventure are that I now have a completely reassembled Yashica 635, but instead of the taking lens I have installed a pinhole. Using the lens cap for a shutter, of course. I shot one roll with it, will develop it soon. And, the 80mm lens and shutter is now on a lens board for my Cambo SCX. The Yashikor doesn't really cover 4x5" but it seems to handle 6x7cm with no trouble, so I've shot some really close-in dreamy macro stuff on a Calumet 6x7cm roll film back. That roll will be finished in a day, and developed with the other from the Yashica Pinhole TLR.
I sort of like it when things turn out like this.