Hi Mark.
Sorry for the delay response. I actually had something similar sounding occur in a new 1¼" clicklock, not on the MBII. Only a few eyepieces had the problem that something was just slightly too narrow to allow them in. It appeared to me the visible compression ring inside was the problem. I had to send it back for replacement, but suspect that back at the shop they opened it adjusted it, and returned it too me. Either way, the problem was solved.
The holders on my MBII do not have a visible compression ring, but near the top I can see the 3 rollers that grip the eyepiece on locking. They wouldn't cause the problem you described. But below each of them I can see a silver dot that can only be the bottom of something like a lug or screw inside the mechanism. They seem to be the right depth to cause what you describe. I wonder if in your device they are not correctly set. If you run your finger around the inside of the holders, can you feel any of them protruding, even if ever so slightly? I cannot feel them in mine, but if you can, then maybe that is the problem.
Prompted by this matter I removed my MBII eyepiece holders because the grubby prism surfaces needed a good clean. A very small Allen key had come either with the MBII or another Baader product for such times - but I did not try pulling the holders themselves apart, so cannot give any advice there. If you can feel one or more of those things protruding then perhaps at least that holder needs to be replaced.
Barry
Forgot to add: when I removed my holders I discovered that on one side the very thin plastic washer type ring that prevents the bottom of the eyepiece hitting the prism was not seated properly, and was somehow bent out of shape. It was able to be seated correctly again after clearing, but it was a surprise to see and I was left thinking it had been like that form the beginning.
Edited by Finbarius, 05 February 2025 - 09:54 PM.