The fix is simple if your machine shop has a lathe and someone with enough experience to use it. Set the balancer up in a 3-jaw chuck using the balancer snout and a strip of brass to protect the seal surface, and have them machine a step in the inside diameter of the hand crank lugs big enough for a flat washer to fit. They will probably need to use a carbide cutter bit since it's cast iron. It eliminates the hand crank function, but it's unlikely that's important unless you're building a 100 point show truck.

If your machinist can't figure it out, box the balancer up and send it to me- - - -I do it all the time.
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!