Over two nights I centered and then tested the collimation with star tests. To eliminate nebulosity being a problem for star detection, I used the Ha Continuum filter as a star field.
After:
It could be done a bit better. The challenge is that the flange around the end of the scope is pitted from previous grub screw use. I wrapped this flange with some teflon tape to help smooth the surface to avoid the adjustment being compromised.
