The research continues... I'm still not satisfied with the induced circular motion of the focusing rod. After some research, other's have it but call it a "wobble". Looks like it may be related to the plastic insert not being a tight enough fit, which introduces a displacement off-axis (there's only one set screw to tighten the center plastic insert).
I'm taking it apart again (for the sixth time) to see what I can do to center the OTA brass with the focuser.
https://www.cloudynights.com/topic/7...e-calibrating/