Sometimes you find a vent screw stuck in the plastic gas cap and the gas cap stuck in the tank. PB Blaster and a few days outside in hot sun and problem solved.
Sometimes the know is broken off and remains of corroded thread are stuck in threads of plastic cap. Coat plastic with wax leaving thread clear. place cap in glass, add bleach. Bleach will react with aluminum and clear out the plug. Wax shields the plastic from dulling effect of bleach.
I had some some aluminum threaded rod and ATTEMPTED to drill and tap knob. Takes a better machinist, but, the idea is workable. A simple jog to drill hole in rod for cotter pin that retains spring and chain. Thread is 1/4 x 20
At one time reproduced caps and hardware were available at a price you could buy project motors for.
It is possible to make both caps and vent screws from stock, but, that is a lot of time and effort as well as a waste of material.
Louis
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