Another thing that can cause the bow arm to move left is a locked elbow. At the release, there has to be SOME movement of the bow when all that energy is released. If there is a slight bend in the elbow, it will allow the bow to move straight forward towards the target. If it is locked, then the arm will tend to swing left. Remember you are trying to achieve, with proper alignment, all energy going directly towards and directly away from the target. Make sense?