Walk-Behind Lawn Mower: Doesn't cut well
If the mower isn't cutting well, first make sure that the wheels are set at the same height and are high enough not to scalp the lawn. If a wheel is damaged, replace it to ensure that the mower travels evenly over the lawn.
Also check that the blade is sharp and undamaged. A dull blade tatters rather than slices the ends of the grass, leaving the tips brown and dry. An damaged blade is off balance, so it cuts unevenly.
Finally, the engine won’t spin the blade at the right speed to cut the grass cleanly if it’s running poorly, so tune up the engine if it sputters or misses.
These repairs may help solve your Walk-Behind Lawn Mower problem:
Replace a lawn mower blade
For safety and for a cleaner cut, replace a mower blade that's bent, chipped, broken or otherwise damaged.
Tune up a lawn mower
Replace a lawn mower wheel
If the wheel on a walk-behind mower is damaged, replace it with one that matches the size on the opposite side of the mower.