I have a ten or eleven year old Yard-Man snowblower with a Tecumseh HSK70 engine. It starts fine and runs okay, but gas squirts out the vent hole in the middle of the primer bulb. It makes lots of nice yellow spots on the lawn in the spring, plus I use an awful lot of gas to clear the driveway. I have to shut off the gas and run the carb dry between uses, or it'll drain the tank - which it did one time while in the back of my minivan. I pulled the float bowl off, and the float seems fine. What am I missing?