oh shucks, that's not what I expected. I had some other bearings left over from a project and replaced the entire rod/shaft with a new one. The roller spins so freely that a full spool unrolls and tangles, so I had to switch back to the original. I would not expect that is a critical factor, but if it improves TPU printing, I have it in reserve. I thought it was a reference to the pinch wheel on the extruder.

I think it's back to the gap between the feed mechanism and even more likely the too-high speed for such soft material.