OT for clarification and admitting my mistake, the camera was a Rolleiflex not a Bolex. My excuse is that I had both in the past.
Back on topic (I have mentioned this before, still fun) when I was 12 or so Grandad asked me to look at his telly (some rental colour job) on a Sunday afternoon, the colour had gone so he took the back off and twiddled all the convergence knobs. The picture was a right mess. I had to do a reasonable convergence adjustment from programme material only (fun
) so the hire company didn't charge him for "fiddling".
As it turned out there was a simple fault to find and the service chap didn't mind about the "fiddling", probably down to Grandmas suburb rock cakes and tea (and maybe a drop of Grandpas Whiskey)! I still wonder to this day what went on his timesheet.