rschurr wrote:a continuous stream of (foggy) air coming out from underneath the breather tube (but still no oil) Rudy
I had the same copper pipe 'mod' in my square back in 1970 (but with the Marzak gear pump, Morgos hadn't been invented).
After a fairly hard run of 50 miles or more, while sitting at traffic lights, I always had a plume of vapour blowing out of the neoprene breather pipe attached to the copper pipe.
And that was in the summer

.
It sounds normal to me.
We probably pushed our bikes harder back then - they were just bikes rather than investments. In 1971 I remember Graham Berry peering over my shoulder from the back while we were heading to the Ferry at Harwich saying "What speed are you doing??"
"85".
"Bloody Hell - you don't half thrash your square".
It stood up to it with regular maintenance and very frequent oil changes

.
Bob.
My avatar shows the late Len Rich in 1970 with the bike I now have - a 1958 Ariel VH