Just so you guys know, the harmonic balancer and the pulley must be replaced as a unit or rebalanced as a unit, or you will break the balancer again. The bolt breaks because the balancer breaks not the other way around. When installing underdrive pulleys, you must remove ALL the balance pins in the rear of the balancer, because the pulley will be neutral balanced.
Jeff
You don’t need to replace the balancer, unless it is broken. It is a good thing to remove the pulley and check the rubber elastomer ring for cracks, over time it will dryrot and cause the outer ring to slip throwing the assembly out of balance and break the bolt off in the crank. You MUST reinstall the pulley in the same orientation (match mark them together so they go back together right), or guess what you will break it again.