I own a Contax IIIA in very good condition, except the shutter would stick on low speeds. I sent it to one of the very well known Leica and RF repair persons in the U.S. who has done work for me before. He really didn't want the job and only agreed to clean up the lower speed mechanisms to get the shutter working at all speeds. At my requerst he also calibrated the shutter speeds so I would know exactly what the speeds represent. For instance, I know that 1/1000 is actually 1/850, etc. I can now use it with confidence until I no longer can. The lightmeter is very accurate as is the rangefinder. It looks beautiful as a shelf queen.
The Contax IIA and IIIA have much simplified and improved shutters as compared to the prewar ones. To my knowledge, there is only one person in the U.S. who will touch a Contax RF, and that is Harry Sherrer. He is backlogged and will only do a total rebuild to a Contax and will not CLA according to e-mails we exchanged. Now if you really want a early prewar Contax, go ahead and buy it, but keep it on the shelf for display. They are beaujtiful to look at and to handle. If you want to use it, you are in for a lot of heartache.