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.
Homelite rewind spring (recoil spring) and container. If the rewind spring is broken, the starter rope won't retract.
Two-cycle engine intake manifold gasket. If the intake gasket is torn or damaged, the engine may run rough.