Champion spark plug (RCJ6Y). The spark plug ignites the fuel and air mixture in the engine's cylinder to power the engine. If the spark plug is has fouled (if the tip of the spark plug is burnt or damaged), the engine may not start or may run rough.
Air filter. If the air filter is clogged or dirty, the engine may not start or may run rough.
Homelite fuel filter. If the fuel filter is clogged, it will restrict the flow of fuel to the carburetor. As a result, the engine may not start.
Carburetor assy fixed jet