Here it that section of the swing broken down even further. Sorry to change the reference numbers :P
#6 left arm moves across
#7-8 ulnar deviation
#9 shoulder starts to rotate
#10-12 a bit of forearm supination accompanies the external shoulder rotation. That the issue?
Is my hip firing late?
Re the take back form- it's a bit exaggerated to control my tendency to supinate too early.
@Chas Tennis: yes, I have started to take a look at the videos after each basket of balls. Helps a lot, at least I don't end up wasting a whole hour if I spot anything on review. Plus it gives me a chance to catch my breath