i am setting up a martin phantom for my dad and i have a question or two. i am shooting a whisker bisquit and i have my knock point slightly above level with the rest. tip of the arrow is slightly down when string is down, but when at full draw, it looks to be level. my question is this. shot it last night, at 10 yards just to get a feel for it and try to sight my first pin. i am getting good accuracy, but maybe 1 of 5 arrows will do something funny with the flight. sorta fishtails, but it is more of a circular motion on the back of the arrow. i have not paper tuned the bow, but it looked like the rest are shooting straight. just every now and then it will throw me a curve ball(err arrow). any suggestions on what this might be or how i can change it?