I use a "long' 1/2" breaker bar with a 3/4" drive socket adapter that fits into the 'square' hole in the harmonc balencer to turn over a stubborn engine. If the engine is nearly frozen one could try an impact wrench to avoid rotating the entire "loose" engine. I have had to partially (nearly copmpletely) dissasemble an old engine to get it to rotate.

HWW

Hoyt, Inliner #922