When I experiment with the spine by changing draw weight, I usually see a movement in the nock end of the arrow. I don' t pay as much attention to where the tip hits, as I do to the direction the nock-end leans. My goal is to get the arrow flying straight for as long as possible. The further away you get, the more likely the nock-end will start moving sideways. If you can get it coming off the bow, perfectly straight, then it will go quite a distance before turning. It' s not clear by your description, which direction the nocks are leaning. Maybe your shafts are very stiff and you need to try something around 70 lbs, or an extra 25 or 50 grains on the tip.