Well, ain't the battery...
Correct, unless you can't get the nut off to turn the crank
That's what started this all... No amount of heat, impact, solvents, banging, etc would get it off. Even once I removed the side cover, drilled holes in the cover nut thingy and applied tons of torque .. nope, fused to the case! Good thing those side case covers are cheap.
I think it's gotta be the gearing behind the starter cover - something in there must not be happy. But, the re-installation SEEMS foolproof, at least. This fool found a way to break something, though...