That wouldn't surprise me. The PO apparently was one of those who thought a little extra 2 stroke oil was "insurance". The mixture was a bit rich when I drained the tank .... 50:1 does not mean 50-50 :-)
I can block off the out "inlet": at the riser. I think for short periods (no more than five minutes) I might be okay - I don't want to run the exhaust "dry" too long for fear of catching the exhaust hose on fire.
Appreciate the help!