If using a Bitzenberger, follow Desperado's advice,Loosen the adjustment screws just a little as a bit snug is best clamp an unglued feather, place on magnet and with gooooooood lighting start at the front of the shaft doing a visual check. The feather should be centered. Now look at the back, you should expect the same results, If not very slightly turn your adjusting knobs until you obtain contact the length of the feather be it 4 or 5". you can make either work with a little patience.