Mine just yesterday, when i made the little Jensen genny powertest, rattled the left flywheel loose from the crankshaft.
Had to remove the governor weights, and loosen the governor itself, to be able to slide it inwards, in order to get to the two flywheel grubscrews, positioned under the swingarms.
For future reference, a 1½mm and a 2mm hexkey is well worth keeping in the toolkit for these.