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.
Walbro primer bulb. The primer bulb draws additional fuel into the carburetor to make the engine easier to start. If the primer bulb is leaking, replace it.