Ulrich, my German is profoundly nonexistant. But semantics does, indeed, play a part in any lexicon, East or West. Confusion reigns here.
'Goggles' presents the most formidable task: what do you really mean? Are you talking about eyeglasses, diopters, or what? I am terribly confused as to what this 'cylindrical frame' really is but I am, nevertheless, am intrigued to help you. The 'looseness' also flummoxes me. It does seem that you are fitting something onto the mount that is a degree off. I wonder if the rangefinder lever (which meets the rear of the lens to determine distance) is really being affected by such degree deviation. But I do not know. Maybe someone else who can 'read into this' will be better at such detection. I never was good at solving puzzles but I want so much to delve into this and present a responsible response. Please help me, more creative types.
You know, Ulrich, my mental density just gave way to the possiblilty that you really are talking about 'goggles' and not a Leica RF camera. I know nothing about such optics but I wanted to advertise to all that sometimes there really is a light bulb in a thick head that has not, as of yet, burned out (albeit, remains dim)!!! - David Lyga