I am checking out a Retina IIa that has two problems. I. Focus - It appeared to focus correctly a few times then stopped. Looking over the lens to what you can see of the mechanism, it looks like the knob moving with focusing, is no longer connected to the arm that moves the mirror. I would say there is a hole on the mirror arm and the knob has worked out. There does not feel or look like there is any binding in the mechanism. II. Shutter - The shutter is cocked but will not release. You can see the button mechanism trying to push the shutter release on the lens, but the release will not move. If you push the film release button next to the shutter release, you can move the rapid winding lever through the complete range again, as if the shutter was not already cocked. But the shutter will still not release. Are either of these common to the Retina? Easily correctable?