One way to ensure that your lawn mower cuts the grass properly is to inspect and replace the mower blade. Mower blades have a cutting edge at each end. The key to replacing the mower blade is installing the new one properly. It is common to install a blade upside down. When this happens, the lawn mower will not cut correctly, or it could damage the mower. There are several ways to make sure you have your lawn mower blade on correctly once you've installed it on the mower.
Find a stamp or etched wording on the face of the new blade that says "Toward Grass" or "This Side Down." Most new blades have wording stamped on the blade to indicate which side should face the ground when you install it on the mower.
Turn the blade and find the cutting edge on one end. The cutting edge is sharpened to a point with an opposite trailing edge. The dull trailing edge is a bend in the blade and should point toward the mower deck.
Hold one side of the blade firmly in one hand and hold the deck with your other hand. Pull on the blade with your hand. If the blade rocks, make sure it is on the shaft properly, and tighten the securing bolt with a socket wrench.
Tilt the mower back on its wheels once you know the blade is on correctly and secure.