Rather than just robbing the rear lens and frame I would be changing the entire viewfinder/rangefinder unit? I cannot otherwise see how the folding viewfinder is attached.
Yes they are almost identical. The Moskva hasn't the same nice finish as the Ikonta but right now who cares.
I did have success last night freeing the stuck shutter. I could not get the inner lens of the front element out, yet the shutter gradually closed in the process and now appears functional.
The inner lens element can be difficult to remove without a proper tool that grips the inner lens assembly. If you crush, distort or in anyway damage this the focusing element will not work smoothly or not at all. Micro tools has the wrenches.
I know I will have to refocus it finally. Unfortunately, the marked focus ring must also be on that Jr.High playground. From pictures it appears the ring from the Moskva may fit the Tessar. (?)[/quote]
At this point I realize that you wish to really get inside the camera. If this is a camera that is precious to you I would strongly suggest Jurgen at Certo 6. The camera is worth a lot of money when completely functional ie. $300 to $700 or more, depending on condition. It may need a bellows, the shutter may need a good CLA, the lenses may need cleaning etc. If the lens is a "Opton" Tessar the inner glass elements are coated and exquisitley fragile. There are things that could happen to your beautiful old camera that could really destroy it.
When properly repaired and adjusted this will be a camera to use and really enjoy as I do mine. Your camera is a heirloom as well. Please use caution.