Richard G. :
Just a note, if you by chance do get some gas without ethanol in it, remember that you'll again want to adjust the carb slightly leaner. In adjusting the high speed, I was taught to start with the recommended setting (usually a turn and a half from bottomed out)run the needle in (leaner) until you could hear speed fall off, back it out through the good running range until you found that same point on the rich side and then run it back in just until it cleans up to avoid running too lean and overheating.
One of the things we tend to forget when adjusting small engine carbs is that they are designed for engines that are designed to run at a fixed speed, so all of the designs that went into automobile carbs to accommodate varying speeds, acceleration, clean idle, etc. are pretty much missing. This means that what you always end up with a slightly rich mixture to prevent "bogging" when the load increases or during the transition from idle to running speed. But again, I can't believe you'd not have an issue with the spark plug if it's been bothering you for two years - that would be way too rich to not carbon up the plug..
Too bad Delphi couldn't whip us up a FI system for small engines, but then we'd have O2 sensors, Map sensors, Throttle position sensors and a bundle of snakes wiring to deal with - and we could pay DynoJet to give us a tuner for it...