The front crankshaft hub is a 2-piece item bonded together with a strip of rubber. The timing mark is on the outer ring. Once the parts slip in relation to each other, there's not much way to fix it- - - -just replace it. The 230/250 engines are still pretty common in the wrecking yards, so a good-condition used balancer might be an option. A new one isn't terribly expensive, however. There's a center bolt with a big flat washer, but the hub is also a press fit. You'll need a 3-prong puller that bolts to the center hub to remove it, not the hook-type puller that grabs the outer ring.
Jerry
