Small Engines (Lawn Mowers, etc.): Cub Cadet LT1018, air filter element, briggs stratton

Question
My husband's lawnmower quit working. Cub Cadet LT1018 with a Briggs Stratton 31Q777 engine. When he turns the key, all he gets is alot of cklicking noise and the flywheel kind of tries to turn but doesn't. He put in a new spark plug but still the same.  Any idea what could be problem?

Answer
The battery has to be fully charger.  The reading should be 12.6 volts.  What you are hearing is the solenoid engaging.  From there clean all grounds, there are more than one.  Be sure there is enough oil in the engine and a clean air filter element. Try this first.