Well since the BellHiller is so much more responsive than stock then Im guessing that slight bend in your shaft is whats causing problems.Especially the fact that it was OK before you added the BH. Since the BH tightens up the cyclic response it only makes sense that it wobbles more. Less slop. Id consider changing that shaft. Even if its not the problem at least youll have a spare on hand. But to me at least it sounds like the shaft