537338701 Trimmer Head Bump Knob - Pack of 4

537338701 Trimmer Head Bump Knob - Pack of 4

Key Features

• Package includes four (4) trimmer head bump knobs.
• Constructed from durable, high-impact plastic for extended service life.
• Enables the tap-to-advance line feeding function of the trimmer head.
• Designed as a direct replacement for the original part to ensure proper fit and performance.

Replaces / Cross-Reference Part Numbers

• 537338701

Compatibility & Fitment

• Fits Husqvarna T25 and T-25 model trimmer heads.
• Compatible with specific Husqvarna string trimmer models including 124L, 125L, and 125LDx.
• May also fit select Craftsman trimmers that utilize the T25 trimmer head.

When to Replace

• The existing knob is visibly worn, cracked, or broken from repeated contact with hard surfaces.
• The line feed mechanism no longer functions when the head is tapped on the ground.
• The knob is damaged and fails to hold the spool securely in place.

Installation Tips

• Disconnect the spark plug wire before performing service.
• Unscrew the old knob from the bottom of the trimmer head. Note: This component may have a left-hand thread, requiring a clockwise turn to loosen.
• Remove the spool and spring to clean any dirt or debris from inside the trimmer head housing.
• Install the spring, the spool, and then thread the new bump knob on until it is secure.