I've got a 15 year old Craftsman 5 HP snow blower that until recently was in great shape. Last season I didn't drain the gas for the summer, I just added gas stabilizer. Now that Denver is in the midst of a big snow storm, I can't start the engine. Spark plug was replaced last year. Any suggestions? An online reference with engine diagrams might be helpful for me because I am handy, but unfamiliar with these engines. I think if I can at least get it running somehow, if there are any gas issues they will clear themselves up.