I have a Retina Reflex IV. When I got it, I had a problem winding film (ended up tearing it), and fortunately I was able to get it fixed for not too much. Why bother with such cameras?
1. The Schneider-Kreuznach lenses are excellent and worth dealing with the cameras for. I suspect the same goes for the Rodenstock lenses too if that is the version you have.
2. Leaf shutters are better for flash synch, so this could potentially be a good 35mm flash camera.
I also have a IIIc with a Rodenstock 50mm f2 Heligon, and love it also. The Retina rangefinders are amazing cameras.
As a repair tip, there is of course Chris with Retina Rescue, but I think he is in New Zealand. But, Ross Yerkes in California worked for Kodak for many years and repaired Retinas, so is a good more local source who knows the cameras.