What does the inside of the balancer look like?
That crank looks like the balancer was beat on and tightened with a hammer insted of honed to fit.
Balance job? Dont take anything to that machine shop.
No signs of hammer abuse. I no expert but tend to agree with moper above in that the balancer was unable to handle the excess harmonics. Must likely do to a lack of a quality balance job and or possibly no balance at all.
This is the result of ignoring the symptoms. But of course I am open to other opinions as well and will ultimately be fixing the engine. I would say the crank came out the worst of coarse but the inside of the balance has some of the same damage that may be able to be honed out.
