Noise from lower sump. Rebuilt yd25

[BenQ]

Yd25 ngine originally had water I sump for a few months. Just rebuilt. noise coming from upper sump. Seems to be coming out of balancer shaft assembly and not further up where crank is. Replaced with second hand one, noise still persist. Has anyone ran into this before.

 

[BenQ]

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[BenQ]

I've managed to work out what it is. Balancer shaft sprocket in front of the crank has a chipped tooth. Ran without balance assembly noise has gone away.