Recently I put a Vixen R200SS into service as a visual instrument on an alt-az mount. The 2" eyepiece holder on that is not very good, being just a tube with two tapped holes near the top for some thumbscrews. (Not even a brass compression ring) But at least it has a 2" thru bore and I can use an Explore Scientific coma corrector with the adjustable top. The difference in the position of the laser spot between "no thumb screws, push the laser against the focuser" vs using thumbscrews is about 1/4". And there's a further 1/8" variation depending on how I tighten the thumbscrews. Also, the coma corrector plus 2" eyepiece is REALLY heavy, so I'm worried that the tilt of that will be different than the laser collimator even if I try to be consistent with the thumbscrews.
What should be my procedure when trying to collimate this? Maybe collimate with the coma corrector already installed?
Suggestions on how to "fix" the eyepiece holder? Maybe put two strips of tape down 120 degrees apart, and then drill and tap a new hole opposed to these two strips, and halfway down the length of the eyepiece holder. Kind of a poor man's parallelizer.