Thanks Gadge
That rundown on the cutout switch is quite complex and I will give it more attention.
The only things I have done since the engine stopped and wouldn't start are:
1. lightly clean the points with emery paper, but it wouldn't start after that
2. cleaned up the engine with degreaser and water. This may have affected the cutout switch.
So I'm not at all certain why it stopped and why it started later.
