I could be completely off tangent but the balance shaft is not something that you balance - its reciprocating mass cancels out vibrations from the crankshaft/pistons/valves etc which are a problem in a V6. From what I've read, its the bearing/s that fails on the balance shaft and I'd imagine the shaft then oscillates and thumps/clunks or rattles. I could be completely wrong however.
you're right.
It sits above the camshaft and rotates the opposite away from it.
I reckon it would be a bastard to fix. Have to take off the timing cover etc.
