Some good videos from Matt Ellis (Elite Throws Coaching & Primal Athlete Training Center in Rhode Island) on drills to prevent dropping the heal in the middle of the circle for rotational throwers. Thanks Ken for forwarding the link. https://www.youtube.com/watch?v=bD11KTWkIEs&list=PLwNEKwFCWvPRA8d-YSzZbWdPbV8fQkMKg&index=6 John Godina Wall Drill: https://www.youtube.com/watch?v=0UrTdAN_OW0 Rotational Shot Put Drills: Wall Series By Coach Joe Frontier, Throw Big Throw Far https://www.youtube.com/watch?v=3ZQ4g3HCJEs Old School Float-Float Sting Video from the 70's (don't laugh too hard): https://www.youtube.com/watch?v=j3oBovzLw6k
(Pay more attention to the demo of this drill by Matt Ellis at around 12 minutes into the first link. I prefer to see you catching and holding the power position.)