but with all i have said above, as a final confirmation of whats happening inside the engine, i would still pull the plug and stick a screwdriver in the hole to feel the top of the piston and then turn the blade and see if the piston moves, if the piston does go up and down or in and out when turning the blade then the crank shouldnt be broken, yet im still at a loss to help you find out whats going on with it. i have never had one with a flywheel brake to know how to disable the brake to turn the flywheel