I guess it depends on what you mean by "work on". We used to have a sign in our auto dealership shop that said "We don't work on cars, we fix them". The other sign said "Labor rate is $20 an hour (this was way back when), $50 an hour if you worked on it first, and $200 an hour if you want to watch". Nothing more annoying than the latter.
I've had those cameras apart, but never had to go very far into them. Some things are easy to access and fix, some are not. The shutter noise on both my GS645s and 690III drove me absolutely crazy, to the point that I had to sell the cameras (the 690 was also sold because it was just too darned big. No, it was actually huge). I never did figure out a way to get rid of that loud "clack", which was really frustrating because a leaf shutter itself is nearly silent. I have no idea why Fuji made those cameras like that.
