Sadly inexcusable treatment for their premier product. C14s. should be walked through by hand in my opinion.
The complaint they misplaced a returned OTA ticket, or did a simple CLA without repair, is one I've read too many times here, although they seem to do it right eventually.
If your optics delivered that performance when new, they will again. If they changed no optical surfaces, that only leaves alignment and, afterwards, collimation
Were the loose screws the ones on the outside of the cell into the tube? It sounded internal in an earlier post and I have not seen an internal layout of the C14. Loose cell to tube securing screws sounds very logical based on smaller OTAs.
If they are the outer screws, any shift in rear cell angle will shift the baffle and primary axis angle.
Than might explain the direction to invert the tube to take up the screw hole slack when tightening.
But things can shift a bit when tightened, a major source of aggravation squaring three screw refractor focusers and even collimating my slip in and slip over 5 and 6" Jaeger refractor cells, also three screw secured. Set, test, reset, test, repeat, repeat, repeat. A pain. But the results are worth it.
In optics those tiny shifts jump out at you when testing.
Also there is no way to determine the original cell position when they aligned it, and that position was the foundation for the alignment they did. I would assume C14s get the effort required to center the baffle in the tube.
The paper target method should give at least as good, and likely better results than I got. The holographic projections are fat enough to put judgment into the mix.
So I would not buy one just for this.
When I look at my holographic projection efforts, they really don't differ in intent or effect from the simple paper circles with an accurate center dot.
I never wanted to pay the Glatter prices either for infrequent use, so I watched classifieds for a long while.
I would certainly try the paper circle/ wide painters tape method. The painters tape was a CN post suggestion and it solves the securing and no residue problems. It could also form a substrate/holder for a more conventional paper centering circle. There are ways to place a center dot accurately.
If the rear cell was loose, the Wilmslow baffle runout reduction method might be a good place to start. No tools needed IIRC. But...
If shifting the rear cell to be parallel to the front cell, and the front cell to then be orthagonal to the baffle is the goal, perhaps placing the OTA face down on a regular mirror might allow use of a conventional laser with a 45 diagonal or ground glass visible return target face.
That should provide a really simple and safe way to test and if necessary, adjust the placement of that heavy rear cell?
If the front and rear cells are parallel the beam should return to the center of the laser face. I assume accuracy would match the target method.
If you try a horizontal OTA method, I have used a wood or plastic carpenters miter box as a stable OTA horizontal rest, and they can be screwed to a table for stability.
A big sharp C11 or C14 is a relevation to use. Worth getting it back in shape.
My apologies to the OP Potamus for the thread shift, but I think the info and discussion may help with the OPs alignment issue, still hoped to just be a 180 spun corrector / secondary.
Edited by markb, 08 October 2021 - 09:33 PM.