Simply for the sake of completeness, I feel the need to make two more comments:
1. I imagine that the reference to the two frames showing a "finger hook" on the lead pipe are in fact the image of Bix's first finger of his left hand gripping the bell pipe in that unusual way that we now know that he did (as can be seen in other photos).
2. What I believe to be shadow (because the image disappears in other frames), but may on the other hand be the diagonal stay on the Bach, is at the wrong angle. Although later Bach's had a diagonal stay, Bix's s/n 620 has a near horizontal stay (as can be seen in the image that was downloaded here).
I am now off on holiday and, as I promised earlier, will endeavour to upload images for comparison upon my return (but I will need help as I am a technophobe !)