Mike -

I suggest you check a couple of items before you jump right into dynamic
balancing:

1 - Check the track of the blades. They should track within about 1/16 of an
inch. If they don't track try removing the prop, turn it 180 degrees, and
remount it.

2 - Check that the blade angles are the same using a propeller protractor. They
should match within about two tenths of a degree. This can be done on aircraft
or at a prop shop. If you take it to a prop shop ask them to check the static
balance.

Dynamic balancing cannot cure an aerodynamic imbalance. Since your engine/prop
combination was smooth prior to the prop work it seems logical to assume a prop
problem or an installation problem.

Ted Stanley - A&P-IA