Drain the fuel tank if it's been more than 60 days since you last operated the snow thrower. Water might have entered the gas tank, or the gasoline and oil mixture has degraded. This is one of the most common problems for engine failure. Tilt the snow thrower on its side and open the fuel tank. Empty the gasoline into a tray or container and dispose of it following your local laws. Refill the gasoline and oil using the Toro approved 50:1 ratio. Mix 1/2-gallon unleaded gasoline with 1.3-oz. Toro two-cycle engine oil. Replace the cap and restart the engine.
Clear the discharge chute if the snow is not being propelled during operation. It's possible and common that snow becomes packed and builds up along the sides of the chute eventually creating a complete blockage. Turn off the snow thrower and wait 30 seconds for the blades to completely stop. Use a small hand shovel or broomstick to clear the area. According to Toro, never use your hands.
Inspect the rotor blades. If the rotor blade has worn past the indicator hole then it must be changed. Also inspect the scraper, which picks up the snow and moves it toward the propeller blades. If the thickness of the scraper is less than 1/16-inch, or you can no longer see the indicator groove, then this must also be changed. Inspect both these items yearly, and take the machine to a service center for replacement if needed.
Let the engine run after you finish using the snow thrower. This prevents freeze up in the parts, making it difficult to start the snow thrower again. Remove as much ice and snow as you can from the snow thrower. Pull the recoil starter handle a few times and press the electric start button once to prevent freeze up of these components as well.