I read alot on the xbow forums, and the movement of those adj is a common problem. There are a couple of ways around it, but all are mostly to pin or epoxy it in one position and then go to a multi aim point system like a red dot w/ three dots or a scope w/ several aim points. The last and least favorable to me would be to fix it in one spot and if you stay w/ single red dot, just learn the hold-overs. I'm very partial to the Vari-zone scopes, got three and they are all dead nuts from 10 - 50 yds. I really don't like having to try to remember hold overs, because now you have added another variable in the deal besides range.[memory] I use a range finder like it was welded to me, lol and the v-zone does the rest. Good luck!!