About a year ago I needed some work done on the filling system of one of my CS pens. I sent it to the person who, previously, had served as the authorized repair person for CS in the USA. When he was unable to repair it we were in a tough spot with no place to turn for help. For a while it appeared that I would have to use the pen (or what was left of it) for parts. Fortunately, the repair person was able to find an independent pen expert who was able to improvise a solution.
This particular pen was one CS produced in their later years when they were trying to survive and they began to so some stupid things with their filling systems.
Given what I now know, I'd be wary about purchasing a CS unless I knew someone who could manage the unique problems that these pens could sometimes present.