The Finish Drill, The Large Muscles Drill, The Stop Rotate Drill, The Gap Drill, will all help teach you. If you just put the time in, it will pay off. Remember to keep the face square on the Gap Drill and only try to hit like 40-50 yd. shots. It is about repetition and solid contact. Now, the shoulder movement in putting stroke, is different because, "Push down pull up", creates a perfect straight back and straight through path. Also, we don't need much length for the stroke and push down pull up is more reliable. Our golf swing shoulder movement is rotary. We don't want that for putting. One big key for the putting stroke to work is, the club must be barely off the ground so the brain can detect the total weight of the arms/club hanging, to tell the shoulders how to move. Make sure you're not leaning on, or resting on the club on the ground. The stance must be athletic and balanced. AND... never let the hands flip or release the putter head. The wrists are "fixed" with the shaft leading the entire stroke.
Move Less ... Get Good! DUPLESSISGOLF