OK, I have "inherited" an old Cox Model 09F3 Compact Tractor from my Dad (RIP) which has developed a "not starting" thing.
I was mowing along when I saw some smoke escaping from a pile of loose cuttings and oil accumulated around the bottom of the oil filler near the starter motor. I flicked the grass etc away and the engine just simply stopped with what sounded like a disengaging dog clutch "clunk". The motor will now not start at all, the starter motor turns, the flywheel turns really fast, but there seems to be either no compression, or a disengagement from, the crankshaft.

I'm not sure but the manual seems to indicate that it has a "engine cut-out switch" somewhere attached to the wires that I see at the location where the smoke came from.
There's also a diode there attached to a connector,and I am wondering if that is burnt out (causing the smoke and the cut-out to activate). IF so, where the heck is the switch?

I'm not totally new at engine maintenance, but unable to lift the flywheel off to see if that's where the switch is.

BTW, engine is a B&S but I cannot find a serial number anywhere.