To troubleshoot a snowblower that doesn't start, check the carburetor, replace the fuel, and clean the spark plugs. If the machine doesn't clear snow well, clear the chute and housing, and examine the auger.
When a snowblower sits unused with untreated gas in the tank for long periods, sediment can accumulate in the carburetor cup, preventing the engine from receiving fuel. Check the carburetor, and hire an experienced technician to clean it if needed. If the snowblower doesn't start when you try to turn it on for the first time of the season, siphon out the old gas, and add fresh fuel before trying again. Ensure the spark plugs are tightly attached, and clean them if they appear dirty. If this doesn't solve the problem, replace the spark plugs, ensuring adequate gaps.
When snow and ice build up in the housing and chute, snow is unable to move through the exit path, inhibiting performance. Turn off the snowblower to clear out any blockages before trying again. If it still doesn't function well, ensure the auger is moving. Replace any broken shear pins, and replace the whole auger if it appears to be damaged. If simple troubleshooting procedures do not fix the problem, seek the help of a qualified repair technician.