Trying to start an uncooperative lawn mower can quickly become a frustrating ordeal, especially since most small engine repair shops place a high premium on their services. Most often the lawn mower's problems are related to a lack of fuel or spark, the latter of which is caused by a bad ignition coil. Fortunately, ignition coils are fairly easy to replace with only a few hand tools, allowing you to save your hard-earned cash by not hauling your poor mower off to the repair shop.
Locate your lawn mower's ignition coil by opening the lawn mower's hood or removing the engine cover and locating the spark plug. Pull the spark plug wire off of the spark plug and follow the wire to the component mounted just below the motor's flywheel. This is the ignition coil.
Use a pair of needle-nose pliers to gently pull off the small "kill" wire that is attached to the ignition coil. This wire stops the motor by grounding out the ignition coil. Unbolt the ignition coil from the motor using a screwdriver or socket wrench, and pull the coil away from the motor.
Install the new ignition coil by loosely bolting it into place. Attach the "kill" wire to the coil and plug the spark plug wire onto the spark plug.
Insert a business card into the gap between the ignition coil and spark plug. Tighten the ignition coil's mounting bolts and spin the flywheel by hand. The business card should move along with the flywheel as it turns. If the card binds or prevents the flywheel from spinning freely, loosen the ignition coil bolts and reposition the coil slightly before testing again.
Lower the mower's hood or replace the motor cover.