I had a bit of a wobble on my stand-on-one-leg movements today. Breathing was good, posture was good, zipper was good — that is, I used the pelvis tilt correctly — and speed was acceptable: I took about 17 minutes to do the form, though I rushed through the Qi gong exercises.
The wobble appeared to be derived partly from the foot, which was not ever quite stable on the floor. There was also some instability in the ankle, from side to side. This far along into the process, I’m always amazed how small movements in the foot and ankle translate into what appears to be an enormous balance problem for the head. Some of it appears to be the challenge of becoming aware of small movements, though.