Picture a ceiling fan spinning slowly and swaying back and forth. The reason for this sway is due to one blade being heavier than the others. Increase the fan speed and the swaying will turn into vibration.
In your plane this imbalance can cause premature prop shaft bearing wear, crankshaft problems, and place unnecessary stress on the air-frame causing cracks and loosening hardware. Let’s not forget about added fuel costs due to this inefficient prop to engine relationship.
A new or overhauled propeller will be static balanced by the propeller shop just to make sure each blade weighs the same. But once installed on the aircraft, the propeller needs to be paired to the engine for proper balance during operation.
Dynamically balancing the propeller to the engine while its at cruise RPM will ensure a correctly balanced and vibration free setup. Any imbalance between the engine and the propeller will be corrected during this process.