What would cause this? History: About 4 years old, used one day a week on about a dozen lawns. Has always started on the first pull and ran great. Never needed anything but a clean air filter every few hours and a new spark plug about twice a year (I always knew it was time when it required an extra pull to start) and a new fuel tank with lines last summer. About two weeks ago, it had been running perfect all day. Get to last job of the day and it won't start. I finished up the job with the Billygoat vac. Put in a new plug in the blower and it started right up but smoked and smoked. Eventually all the fuel burnt off. I figured the smoke was from fuel sitting in the muffler from trying to start it earlier. Ran great for a full day of cutting. Then today, a week later, I notice gas leaking from somewhere on the carburator. It won't start again and the plug is black and dripping wet when I pulled it. What could be causing this? And what do I need to do? Thanks a million in advance!