These were a perfect fit. Lefty is the steam knob bolt. I know it looks narrower, but it screwed with little resistance all the way to the hilt. The M8 nut also worked on the steam knob bolt. Sidenote - I clearly have no idea how bolts are measured. The Bakelite (?) knob itself is 40mm long, 25mm diameter at the widest, 19mm at its narrowest.
