Slight kick back on the starting handle

[Bob Culver]

On the topic of hot tube ign, during the Depression my father acquired a Rudge multi engine to drive his lathe. But the magneto condenser had failed and he coud not afford one. So made one out of silver paper and mica. He said it produced 3 sparks. He then made up a hot tube and ran the motor on that until an electric motor was acquired. (Similarly the home made radio ran off a home wound transformer and a chemical rectifier; rather like an open battery cell.)
Running the Seven later was not a problem!