Toro 31230N Operator's Manual page 25

Blade Maintenance
Maintain a sharp blade throughout the cutting season because
a sharp blade cuts cleanly without tearing or shredding the
grass blades. Tearing and shredding turns grass brown at
the edges, which slows growth and increases the chance of
disease. Check the blades daily for sharpness, and for any
wear or damage. Sharpen the blades as necessary. If a blade is
damaged or worn, replace it immediately with a genuine Toro
replacement blade. Refer to Servicing the Cutting Blades.
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