is the balanceer worn out?
It's a steel core that is (should be) a press fit on the crank shaft.
Then a rubber isolator supports the steel outer part.

The rubber deteriorates over time, if yours is failing it may wobble and knock.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-