I dismantled mine. I think I know what drives positioning. Within one of the half cases there is a simple black plastic strip bent around the inner wall of the housing. This strip has markings, actually light reflecting portions that I have highlighted in the picture.
On the rotating barrel...
Unfortunately mine is way out of warranty and in Europe they will not swap it. So either I buy a new one or try to pry open the current one and fix it. If it is only about changing the flex circuit I am sure I can make it, the challenge is the method to open it.
I checked your very useful link...
My Colormunki shows the same symptoms as yours. I'd like to open it up, maybe I can fix it. I understand that you have to pry apart the case, but I have no clue where to start the procedure. Can you help me or point me to a guide? My searches on this were futile.