Found it after an ascent in pouring rain, together with namklaw and cache-dog Nash.
With Walter's description, the cache is easy to find even on a foggy day like today.
The innkeeper at "Dümler-Hütter" is informed and watching the cache from his window with binoculars, so be sure to behave!
Combining this cache with GCNX7T (Piessling Ursprung) led to a nice 6-hour rountrip.
If this cache gets the number of visitors it deserves, a logbook could be more appropriate than the actual logsheet.
Pictures will be added later.
TFTC and thx to namklaw for the enjoyable company,