Generac GP5500 - not starting

I have a Generac GP5500 (model # 0059396) machine. Its a 2012 build with about 50 hours on it. Those hours were put on it primarily back in Oct 2012, and then the unit mostly sat unused. I did drain the fuel before storing it. About a year ago, I tried to get it fired up again, and couldn't get things going.

I recently swapped out the spark plug, put on a new fuel filter, and replaced the air filter. I put some 4-cycle TruFuel in the tank, and it just won't start. I get nothing.. unless,...

Generac GP5500 - not starting