When I wanted to exchange the hyperstar lens with the secondary mirror, I noticed, that the mirror housing was loose and turned easily. That of course, would throw off my collimation each and every time. I contacted Starizona and they are selling a gasket that will keep it in place. Luckily they have a video that walks one through the process of installing it. But I probably will have to remove the entire corrector plate - yikes!
I also contacted Celestron support and asked for advice how to fix this - their response was to send in the entire OTA and they will fix it for me (within the 6 weeks timeframe). Not superhelpful...
After 2 weeks, I received the gasket and went right away to install it. I watched the video a few times and it looked easy enough. But of course it wasn't! :-( After I removed the screws and the retaining ring, I wanted to remove the corrector plate - which looks insanely easy in the video. But it didn't move a bit! After closer inspection, I noticed 4 little screws on the side of the corrector plate. These can be used to center the corrector plate:
So, I loosened all of them a little. And with a little screw driver, I could verify that the corrector plate can now move. But still when I pulled on the secondary mirror housing nothing happened. Upon further inspection, I noticed some rubber that was in three places and seems to connect the corrector plate with the tube:
Turns out, I will have to cut this silicone in order to get the corrector plate out. I did that, after that everything was pretty easy: removed the baffle tube, inserted the gasket in the mirror holder, attached the mirror holder and screwed the baffle tube back in. Then I inserted the corrector plate back. Centered it - that was a little tricky. And finally screwed the retaining ring back on.
Of course, the scope is completely out of collimation now. Will do that at the next clear night.