I am yery happy about your answers. This proudness of the bearing out of the case made me wonder like crazy. Assuming everything is fine with the axle and the spacing on it, the problem must be on the side of the crankcase cover beeing to tight to the primary gear and allowing no gap between.
As you can see here...
The cover was involved in several crashes... it was repaired by welding, means of aluminium plugs, grinding, inserts and paint...
but wait, is the whole basement of the bassin sunken in?
So far, I thought the cone is original... seems like remains of a former crash
I'll try to fix it. As a precaution, I am looking now for a new used cover. If anyone got some spare parts, please let me know.