Yes NormK, I found that out the hard way. I have a Masport that was given to me because it would not run, an extremely clean mower with catcher, investigating I found the carby/governor spings etc all fitted incorrectly and the key for the flywheel did not exist.
One of the fisrt things I do when I bring a mower home is pressure wash it completely before taking the engine off, when pressure washing under the mower I noticed the cutting disc moved, it was cracked and when I went to have a look fell of in my hand so imagine the mower was pulled apart to find the noise.
As I collect older mowers and advertise for freebies I do end up with some mowers that are not what I call collectable but too good for scrap, so have been doing them up to go to my local mens shed for them to raise funds or to donate to a worthy person.
Got off the track here haven't I, anyway got the motor all back together and mounted and went to start it not once but bloody twice. my right hand was in pain for over a week lesson learned, still have not started the Masport yet as am waiting for a donor mower to get the disc off.
Beech