Should I allow the bending and straightening of the elbow pull and push my shoulder back and forth?
Your Shoulder will 'open and close' only horizontally -- like a door --but then only minimally. Focus on your Right Elbow Bending andStraightening while your Right Wrist remains Bent and Level with thedowel as a Rigid Angled Extension of the Forearm. Your ShoulderMotion should move only as necessary to accomodate that action.
Remember, everything stays exactly Horizontal until you get the Feel ofthat Motion, i.e., your Right Forearm Flying Wedge With Dowel staying in thesame Horizontal Plane. Only when you really have that Feel should you transferthat IDENTICAL FEEL to the Angled Plane of Motion. Your On Plane RightShoulder will now Turn on the Angled Plane (just as it did the HorizontalPlane) to accomodate the new Plane of Motion of the Right Forearm Flying Wedge.
Then, as stated, move the exercise back and forth between the two Planes tomake sure the "Paddlewheel" Motion is identical.