Two things.

#1 is to check the straightness of the shaft itself. If all of yoru shafts are straight then your accuracy will improve.

#2 is to check to make sure that your broadheads are perfectly in line with your shafts. Eleminate the wobble from your broadheads and you will have better broadhead flight.

To use just lay the arrow in the rollers and spin it. You will immeediately notice any irregularities with your shafts or broadheads.