As I understand it....
There are pre-war and post-war versions. The Russian Jupiter 9's are copies of the pre-war lenses, the very early ones contain original Zeiss elements. I have a Jupiter 9 and find it to be pretty good. The quality control was all over the place, but I got lucky. My optics are good but the mechanical is a bit sloppy. Sometimes Henry Scherer has overhauled original Sonnars for sale on his site. I think there are companies that sell serviced and collimated Jupiter 9's.
Good luck.