Mike you want the cables to stay tensioned all the way both directions. Make sure the all the distances from the center lines of the pivots points are the same. Your 4" offset on the control arm also needs to take into account the thickness of the control surface to get the distance from the centerline correct. If that doesnt help make sure the pivot points are in the same relationship to the attachemnt points as well,

Hope that makes some sense and helps you out.