HELP Generator won't start

You are most likely correct in assuming the float or needle valve is stuck. Seafoam is not too effective on something that has had bad gas in it for a long time. Probably all fresh gas and a new carb would be the best solution. Having dismantled many carburetors in my lifetime, the only thing I have ever seen really clean them was an overnight soak in Gunk 'Hydroseal' dip. It's getting pretty hard to locate rebuild kits for carbs anymore as they are becoming considered throw-away items. Rather than Seafoam, I'd suggest Stabil fuel stabilizer in the tank in the recommended dilution. Best thing with the gas is to carry a 5 gallon can of gas and run the MH until it's almost out of gas (the can in case you guess wrong) then put about 1/4 tank in and add the Stabil. Of course it would be better to use the MH every couple weeks to keep everything fresh!