Usually cameras don't get a la carte service, especially folding rangefinders. I asked because if the camera was recently sent in for anything more than re-covering in leatherette, it should have come back working perfectly. If it wasn't working properly, it should have been sent back. If it has been worked on at all after service, then any work done should no longer have any warranty and the customer should have to pay full price for another repair.
I've botched plenty of user and broken cameras in these last decades of learning camera repair, so I know how this goes. Now I'm on the other side of it, I can say that I don't know how to work on a Certo 6 and I'd trust that camera to Jurgen, not take it apart myself, even though I'm confident and competent now in my repair work.
Phil Forrest