engine

[monzanick]

Sounds like its due for a overhaul.
My uncle bought a G tractor that kept throwing the flywheel off, Finally when we got the flywheel to stay on, you could hear the knock. We finally traced it to the pot metal collar on the oil pump had broken so the oil pump wasn't turning/producing pressure. I had figgured it was due to water in the crankcase(drained out ALOT). once repaired, I ran like a deere.

My point is to source the cause of the bearing failure, usually in lower rpm engines its not from metal fatigue. It may have been something simple as improper assembly previously. It might be worth it to talk to your local machine shops to make sure they are familiar with these old engines. There isn't much worse than a machine shop guy learning on your engine. some can do it, some CAN'T.

Hope this helps ya.