After I moved I took my oldest ZM-3b out of the case and discovered that the rear optical elements had clouded. I contacted Arax photo and he had the lens recoated at Arsenal. I am just pleased as punch with the work, they actually multicoated it for around $150. I say around because I also sent a Saluit C that I had purchased at a camera show for $30. It was in exquisite shape but someone had jammed the shutter. I knew the dealer and he sold it with the case, waist level finder and 2 matching film backs. It was added to the pile of projects to do. One day I got around to it and the shutter had miraculously self healed. It was obvious that it needed a good CLA. When I had to send the lens I also sent the camera. I decided to have it converted to Pentacon mount and several other minor modifications while I was at it. I just got it back too and can not say too much about the good workmanship. It is almost as smooth as a Hasselblad in operation.
I have to assume that the conversions that he sells are every bit as good as mine!