What type of gas do you use on your snowblower?
I learned a hard lesson before where my single stage snow thrower's carb needles were gummed up. The mechanic who fixed it (rebuilt the carb) said not to use gasoline with ethanol as it can easily gum up. Ever since 09, I've been using high octane for my snow blower and lawn mower.
He also recommended to empty the tank when the season is over to ensure nothing is left in the engine that could damage the internals.
I did see this article posted in one of the threads pertaining to snow blowers - http://www.msnbc.msn.com/id/25936782/ns ... umer_news/, however it seems to pertain more to 2 cycle engines.