I once had the same problem. I could not stop a nock-high entry even though I almost completely dismantled my bow and retuned it several times. I started blaming the new bow.

I finally sat down and mentally went through all the possible causes. I finally discovered the problem was the tension adjustment on my rest. A very slight adjustment solved the problem.....after a week of frustration.

Not saying that your problem is definately the tension on the rest, but if you are using a mechanical release on a centershot rest, I would not be surprised to find that rest tension is the culprit. Also, if it is, and you start to see the nock-high entry disappear but not entirely, now play with your draw-weight.

However, nock-high caused by shaft spine usually indicates a weak spine. I would think that a 75 grain head on your shaft @ your draw-weight/length would not cause a weak spine issue. But then, carbon shafts appear to have a mind of their own. [:@]