Run the machine until it is out of gas. Place the snowblower on a flat surface. Turn off the engine and detach the sparkplug wire to make sure the machine doesn't accidently start while you are servicing it.
Identify the plastic belt cover on the front side of the snowblower engine. Remove the cover by unscrewing the two screws holding it in place. Tip the snowblower forward so it's resting on the front housing.
Unscrew the six screws on the frame cover, located on the underside of the snowblower, to expose the drive belt.
Pull the idler pulley upward. When looking at the pulleys and belts, the idler pulley is located in the middle left side of the assembly. Lift the drive belt off the engine pulley located on the right upper side of the pulley-drive assembly. Remove the belt from the friction wheel disc. Slip the old belt off between the friction wheel disc.
Install the new belt in the reverse order. Reattach the frame and belt covers. Tip the machine back on its wheels and attach the sparkplug wire to restore power to the unit. Refill the fuel tank.