Hi again!
Thanks for all the answers. However I still haven't found an answer I'm looking for. My worry is that someday when cutting the manetos during the engine run up, the key will get jammed a little in the off position and the engine will stop. I want to know because I'm doing a lot of solo Nav flights now, and if it does happen accidently, I want to understand what happens to the engine, what to do and what to look out for. I've been told that it can be bad for the engine but haven't been really been told why. If its just as Sport_Pilot said, then surely its just a case of starting it straight up again?

Other than that the switch and the mags have been always been fine. The switch works fine when testing the left and right magnetos and the mags themselves have never been an issue. I was in a piper Archer that had a magneto failure straight after take off, I don't no how the pilot caught it but he did and continued to a bog standard landing.