The Jupiter lenses are not common in the US, and few shops have worked on them. Their low cost makes it uneconomical for someone to pay $100 to $150 for a CLA. They tend to be cans-of-worms to work on. Set screws are fragile and break easily, screws are jammed in place, and liberal amounts of grease often make up for slop in the mechanism. Take apart a few hundred of these, still never know what you will find waiting.
I currently have over 20 Jupiter-3's in Leica and Contax mount. Cherry Picked over 20 years. Probably some of the best Jupiter-3's in the world. !2 KMZ lenses. They are the best. Went through more than 10 Valdai lenses to find a good one. And then replaced the front element with one from a ZOMZ, is now really good. The Jupiters- the older the better, if you can find them clean. Those made before 1954 have Schott glass, a good ones equals a wartime Zeiss Sonnar.