great work--I'm glad it's working for you.
I agree with everything you posted. Terry mentions in that video that your balance and stability has to be well established before it's even possible to refine propulsion. I think I am slowly beginning to understand how to do it.
It will be interesting to test myself with a pool and pace clock again. I certainly feel like I am swimming differently than I was two months ago, and much of the difference has to do with the water feeling thicker, and my stroke becoming more propulsive (I think!).
I really have been using Terry's "ball of molecules" visualization to help prevent slippage in my stroke. Also "opening the armpit" (I have been doing a subtle move with my scapula that I think does that). And of course, really trying to develop awareness of pressing straight back at all times, never down. I think I've even discovered why some bubbles appear sometimes during my left arm pressing motion: I have been spearing a little too shallow (I think), which sometimes causes my press to have some downward force to it.
Another discovery I made is that I have started to be able to stretch out my pelvis in a gentle, relaxed manner to lengthen my body. It feels a little like my legs are being held in gentle traction--but instead of someone pulling on my ankles to stretch them out, the stretch is coming internally, from the pelvis and hips. When I do it, it makes my legs feel lighter, more relaxed (no tendency to cramp even during long open water swims), and longer. Stretching from the inside out!
How that will show up in SPL and pace, in fresh water, I have no idea. Perhaps I'm fooling myself...