I took the belt off, put the car in neutral, put a breaker bar on the crank pulley... and it's jammed. Won't go in either direction. The AC spins by hand, as does every other pulley, and the car will roll freely in neutral. As I said, the battery is good. Has 12volts, tests good, and plenty strong.

So, is it worth doing the bearings from the bottom without pulling the motor, or is it best just to get another motor? The pistons and heads seem fine.