imho, go to a workshop, let mechanic open up the carb, let him go for a cigar and meanwhile unload an entire aerosol of carburetor cleaner into the passages (wear glasses). adjust float height. let him reassemble it
replace the power piston with a new one and the accelerator pump diaphragm with a new one. also the mixture screw.
i think you will double or triple the chances of having it fixed
just the zehmat of buying a big aerosol of carb cleaner will make things better.