Interesting. No idea why they had a vent tube AND the rubber seal vent that the accel pump arm lifts ??
In your situation from a few months back with the stuck float, they usually stick to the bottom of the bowl when it dries out, holding the needle open. Pushing may jar it enough to free up, but a short shot of carb cleaner with the straw down that tube may be a better tactic to dissolve the gummy residue left from oxygenated fuel and free the float. No idea if you Canadians have to deal with the oxygenated crap gas, but I only run non-oxy in anything I have a with a carburetor.