Sit or stand up straight facing the pulley.
Hold the handles in each hand, and straighten your affected arm down by your side.
Move this arm behind your back as far as you can.
You may find it helpful to turn your body so that this shoulder is slightly closer to the pulley.
Pull down with your unaffected arm, drawing your other hand up behind your back.
Allow your elbow to bend, following your spine with the back of your hand.
Go as far as you can until you feel a stretch, making sure you are not leaning your body or hunching your shoulders.
Hold this position.
Control the movement as you bring your arm back down to the starting position.