The walbro carbs on the G and H OHV valve engines can be very stubborn to get right. It has to do with the seat that goes up from the bottom of the bowl screw. That seat wasn't made large enough and has problems with clogging. A very fine wire can be used to remove blockage, but NOTHING else will work, not seafoam, chemtool, air, nothing, I've tried. The symptoms of the carb problem is that it refuses to idle, but will run at full throttle, when you try to lower the throttle the governor starts hunting and the engine dies. One of the guys over at GTTalk sells a updated version of the seat with more room, but once cleaned they tend to be okay as long as they don't set for long periods of time or petrol goes bad as month old milk. Attached is the part the guy at GTTalk sells, I'm sure OB probably knows him or can find out, it is the emulsion tube that easily stops up