I have purchased a very clean S2 but it has a couple of problems. The yellow focus area is not visible. There was a rattle inside the RF area. I removed the top cap and there was a tiny rectangular mirror loose inside. I have no idea where it goes inside the RF...
The second problem is that the shutter will not fire. The shutter is cocked but when you press the shutter release the shutter does not fire. I understand these cameras have an issue with sticking shutter.
I have opened up the camera and re-glued the mirror and adjusted the RF for infinity focus.
I cleaned the shutter blades with lighter fluid. While gently exploring the camera I found out that if I press the shutter release several time quickly the shutter will release. Obviously there is something that is hanging up and releases when giggled some.