Your push-style rotary lawn mower cuts the grass with a rapidly spinning blade. After cutting all season, the blade can become dull, and running into small twigs and stones will make it worse. Installing a lawn mower blade is relatively easy. A single bolt usually holds the blade to the engine shaft.
Take the lawn mower to a smooth, level surface in a well-lit area. Disconnect the sparkplug wire from the sparkplug. It should simply pull off.
Put on your gloves and turn the lawn mower on its side. Wedge a wood block between the lawn mower and the mower deck housing. This will prevent the blade from spinning as you try to loosen the bolt.
Turn the bolt holding the blade counterclockwise with an adjustable wrench. Loosen it up completely and remove. Remove the blade and put aside any washers that come off with the blade for reinstallation with the new blade.
Position the new blade into place. Put the bolt and washers back on and tighten by hand. Use your adjustable wrench to tighten the bolt until it is secure.
Set the lawn mower back upright and put the sparkplug wire back on.