Don't keep hammering on the balancer bolt- - - -you'll strip the threads or break the bolt off. Soak the cylinders down for a couple of weeks with a few ounces of a 50/50 mix of acetone and automatic transmission fluid- - - -both are available at any Walmart store. Then use a long pry bar on the flywheel teeth against a bolt threaded into the back of the engine block to get enough leverage to turn the crankshaft. What engine are you working with- - - - -since a stovebolt six doesn't have a balancer center bolt?

It's possible to make up an adapter for a grease fitting from a spark plug shell and push a piston down the bore with a hand pump grease gun to break it loose. Pick out a cylinder with the piston near the top of the stroke, loosen both valve adjustments all the way or remove the rocker arms, and pump the combustion chamber full. Don't overdo it- - - -you can blow out a cylinder wall, crack a cylinder head, or bend a connecting rod if you're not careful!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!