What you will is a spin tester this is the one I made.



Then with a broad head on the arrow place on the tester and spin the arrow.

Look for any wobble in either the broad head or nock, if the BH wobbles try another head to make sure it is the shaft and not the head.

If it is the shaft then get a G5 arrow squarer and square the insert.

If the wobble is at the nock end then mark that arrow and use it either for a plactice arrow ot tomato stake