How about applying your analysis to simply lifting your arm "using the hara"? Wouldn't that be a better practical start?
I was re-reading this thread for thoughts on weight transfer and found this comment very interesting. I recently had an experience that made it stand out. I'm hoping Mike will comment further.
I was doing tai chi, just opening the Yang form, raising and lowering my arms, when I suddenly remembered a discussion of raising the arms "from the center". I realized that I was simply "willing" my arms to raise and letting it happen as "necessary," which meant that I raised the arms with the shoulder muscles. Which is much as Erick describes it in a later post: you activate the shoulder muscles and the body has to adjust from the center to balance the structural forces, etc.
But this time, I just stopped, relaxed, and asked myself, "How could I raise my arms from the center?"
I sort of "pushed" with my abdomen and the arms raised.
Well, of course, the shoulder muscles and all the usual muscles acted, but this was different. Instead of "telling" my arms to raise, I told my center that I wanted to open tai chi and waited to see how that would happen. So the command went from the center through the body (via the fascia?). My arms began to raise and, acting from the center, I felt many small adjustments fall into place, things like letting the elbows remain heavy, equalizing the tension/relaxation in the left and right sides of the ribcage, both sides of the back, the shoulders, etc.
In short, it was a much more tactile experience than just sending a message to my muscles to raise my arms. In the process, I felt much more aware of my "whole body" than usual when raising the arms for tai chi. In particular, I had a much clearer awareness of my whole back and I wondered if this was what was meant by letting the chi "adhere to the back."
Mike's question led to a long and winding discourse that never came back to the point of raising the arms from the center and two years later, that point has never been fully addressed.
So how about it, Mike?
Is the experience described above related to what you meant? Can you expound further on how to raise the arms "from the center?"