Seems like reorienting the elbow has had a significant effect. With the second arrow of the day my teacher mentioned that my earlier problem with the left bouncing right at hanare (before swinging back to the left) seemed to have disappeared, and by the end of the day it seemed pretty decisively gone. Talking about it with him later, and what I was doing differently, I’m pretty sure he knew what was going on all along, but was letting me work it out for myself. In fact a few months ago he told me it was time for me to start doing that: experimenting and figuring things out for myself, rather than just following his recommendations. If he’d just told me what to do, I would have done it and been satisfied with that, but this way it becomes a little drop of personal experience, rather than just something I do by rote. I suppose that kind of discretion, the patience not to correct a student, is one mark of a good teacher.
Of course now, having changed something, everything else is a little out of balance, and it’s going to take a some time before things settle again. Tons of new students at the dojo. Cherry trees still in bloom all around. If I remember my camera I’ll take a picture.
Also I want to thank Ceterum Censeo. While trying to work this out I went back to our discussions in February (starting about here). Very helpful, and I’m not sure I would have put so much effort into the video images if not for those comments and the way you analysed the video of the kyudoka there.