Actually I should call this post MBS Musings since I had these insights doing work there over last weekend and this weekend.
Here are some additional observations :-
i) To push or pull a heavy object aligning the kua properly is the key. Once you can do this you should have no problem pulling and pushing with good power. Its really that simple
ii) Circling properly is the key to spiraling properly. So to master the ability to use spiral power first learn to draw circles correctly. Then learn to interchange from one to the other. I saw this natural phenomena of the wind blowing dead leaves in a circle for a while before the circle turned into a spiral. I took a video and might post it another time.
Then the spiraling became more intense before turning into a circle again and repeating the process. All this while the dead leaves weren’t blown away and was trapped by the swirling wind.
This is why to excel in Tai Chi bridge work to control the opponent’s arm in push hands using a variety of process a good understanding of how to use circling and spiraling is essential.