Pull off your fuel line going to the carb. with the petcock off. If gas flows , PETCOCK problem.. Id buy a new one for $19 unless you can find a gasket kit MUCH cheaper.. If thats not the problem , snap your throttle from wide to off a few times ,,, sometimes that'll seat things.. You could "tap" the carb. bowl a bit with a non mettalic tapper... Screwdriver handle works..If you are still leaking , pull the bowl and replace the float bowl seat.. You could try to clean it a bit before you spend the $4...Leaking fuel from one of the orifices below carb even when petcock is in off position. Should just need to replace seals, yes ?
If so, drain tank first before replacing seals?
Or is it stuck float?