It only turns partially around even without the starter off.... Its something inside, I can hear a clunk when it stops (going counter clockwise) Smooth and quiet, and all the way around clockwise though.
you got the valve cover off? if not, yoink that thing and have a look to see if the valves are moving or you got one stuck (or dropped) that's holding up a full rotation as the piston contacts it.
cars usually don't just get parked.... something happens that takes them off the road. could be minor, could be catastrophic. don't dig too deep or spend any money on something that could be a lost cause. like, i wouldn't be dropping no money on a starter unless the whole thing rolled over easy. and even then, i'd probably go find somebody to rebuild that for a fraction of the cost rather than buy "new".