The Crankshaft bearings as you were wondering about should be good if the motor only suffered piston/ring damage.
A teardown prior to purchase any parts would be the way to go as it may not need a Re-bore; its all speculation at this point
IF.. that is the only piston that shows "symptoms" I would remove the carb. / Intake and from that end remove the end-cap of that particular piston/rod.
and see ???
Yes, it can turn over with seized rings & if it spins with the plugs out.....seems to me that you have a weak starter and/or bad wiring/connections/ground
Jerry, I think Dunbar meant a 3-way/pole switch set-up like in a house
A regular on/off/on spring loaded switch does the job, the switch controls the relays
