This lens came out really good, I tested it with my M9 before sending it back across the Atlantic.
This lens is interesting- a 1953 KMZ optics module mounted in a later focus mount. Best of both worlds. The 1953 KMZ Jupiter-3 uses German glass, and performance is on par with the wartime German Sonnars. I have a couple of those to compare with. The later focus mount corrects a design flaw in the wartime Zeiss LTM mounts and the KMZ Jupiter-3 mounts. Those mounts use ONE SET SCREW to hold the helical in place in the mount. I have seen them "break Loose" and the helical come undone. This later mount uses three set screws to hold the helical in place.
I will not be taking on any more Jupiters to work on for a long time. Too much 7th grade homework to help with these days.
Not the same 1953 KMZ J-3 being sold here, but this is what was done to the lens being sold here:
http://www.ziforums.com/showthread.php?p=2767#post2767
and then the lens was shimmed for optimal performance on the Leica. I tried to convince some other repairman that work on Jupiters to add this as a service, but it is "not by the book". Standard collimation procedures call for the lens to be collimated at infinity. That works if you use the lens on a Russian camera. To work on a Leica, the Jupiters need to be collimated at close distance.