Removing air filter cover from B&S Model 217802-4145 FI

I bought a well used and abused tow behind mower powered by a B&S 11.5 HP engine model 217802-4145 F1 equipped with the cylinder air filter “C”. When I tried to remove the two knobs “A” the studs they are mounted on turn also, short of cutting off everything does anyone have any suggestions on removing the knobs?
Tom


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Removing air filter cover from B&S Model 217802-4145 FI