Speaking of, I have a Briggs Quantum.with a filth ridden carby that was full of greeny brown sediment and foul smelling old petrol. I pulled the bowl off as well as the needle and float and shot cleaner through all the holes I could see. Made no difference. Motor refused to fire and only does so when you give a squirt of ether.
I notice petrol oozes out the primer bulb as well.

Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!