You have to bear in mind that you are almost certainly going to screw up your first repair if it is anything BUT the very most basic camera. and you also need to remember that if you are buying one to learn how to repair cameras and not just to repair a broken camera and sell it, you are going to be taking it apart. You crawl before you walk. The thing about a C3 is that if you screw up, as you probably will, you probably won't break anything and can just start over. An SLR is not a good camera to learn repair with because
1. They are a lot easier to break. Take your finger and poke your shutter curtain with it a couple of times if you don't believe me.
2. They are complex enough that the beginner can easily get intimidated or bogged down and then give up. If a beginner does anything but the very most basic and obvious repairs to them, he will almost certainly ruin the camera, and that will probably be his last repair attempt.
3. They require complex tools, such as a shutter timer (needed for retensioning the shutter curtains) and a volt-ohm meter (for testing circuits).