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These are my modified pulleys. Note the repeating pattern in the teeth. This is the same pitch as the Z axis threaded rod and is caused by the a Z-shaft wobbling a bit as the threaded rods rotate.
The "wobble" turned out not to be a sideways movement at all but uneven lift was cause the layers to bulge every Z-motor revolution.
The Z-motors rock slightly on their flimsy mounts. The fact the hole aren't in the right place doesn't help.
The threaded rod and smooth rods aren't parallel causing the shaft coupling to flex every revolution.
My temporary fix is 4 wedges glued in place.
The results are pretty good.