Hmm. OK let's break it down again.
I think pics 1-3 look OK. The thumb down thing seems to work.
5 looks like a late cocking of the wrist? Or rather early supination...
6 shows my thumb up
OK so I half fixed the takeback
I was aware of the thumb down until I released the left hand. Hopefully now that I've really, really identified it, I can fix it. Fingers crossed.