For those others who have experienced the same seizing of the Baader Clickstop Zoom MkIII I've managed to repair mine and it's a 'relatively' easy fix. The fault is indeed the grease used, somehow I suspect the cold affects the grease used by the manufacturer such that it becomes more like a glue. To access this part of the eyepiece you need first to remove whichever nose piece you're using, the narrow section you then see has a thin plastic shroud which in my case just pulled off with a b