Side Car go look at the engine for him..................
I could, I guess...
I believe his issue lies in the top of the motor, under the flywheel, not on the bottom or under the head (Not sure why he would pull the head anyway). I think either the mag dropped a magnet segment or there was a loose bolt up top that when he laid the motor on it's side, the bolt dropped out and got attracted to a magnet segment and is now jamming against the alternator windings or the ignition trigger.
Super easy to get the flywheel off., take the nut off and wack the crank end with a brass hammer and they usually pop off. If not, a 3 jaw puller works. Had that happen to a Kawolski 27 vertical V-Twin. It dropped a segment and locked up tight. Was under warranty so I had the local mower shop order me a new flywheel but in the interem, I pulled the flywheel, removed the loose segment and put it back on. Ran fine, just a bit down on charging current. Ran that way until the new one came in and then I swapped them out and lived happily ever after.
Reading posts on here, it appears to me that most people on here with issues, tend to ignore the obvious and look elsewhere. Small engines are rock simple. Not much to break really. Not complex either. If you don't make it complex, it stays simple.
Myself, I would have started with the flywheel but that is just me.