When he feels heavy in the right rein/not supple in the right rein, it's because his right barrel is flinging into me and he can't bend around my right leg. Instead of addressing his head.... address his right rib cage... But not by nagging. Get in, get out, get it done. :) Then make sure to leave his right side alone with my leg until I need it again. Remember, I'm training him to be responsive to my right leg and seat, not dull!