Yard Trimmer Repair

Call it a weed whacker, a weed eater, string trimmer, or a goat-on-a-stick, it’s all the same: a yard trimmer. This Fix-It Guide on yard trimmer repair tells how a yard trimmer works, what often goes wrong, how to identify a yard trimmer problem, and what parts and tools you will need to fix it. It then gives simple step-by-step instructions for how to access yard trimmer components and how to install monofilament line on a yard trimmer. This Fix-It Guide also directs you to instructions for electrical receptacle repair, electrical cord repair, motor repair, switch repair, small engine repair, and battery recharger repair for more information needed to fix a yard trimmer.

How Does a Yard Trimmer Work?

Yard Trimmer Repair

Components of a typical electric-powered yard trimmer.

A yard trimmer is an electric- or gas engine-powered tool for cutting weeds and for trimming and edging grass. Yard trimmers come in a variety of sizes, designs, and power systems. String trimmers cut through vegetation with a short, rapidly spinning length of thick monofilament line. Heavy-duty trimmers use rotating plastic or metal blades. Power is provided by electrical cords, electric batteries, or small gas engines. The more power, the more it can cut.

Fix-It Tip

The first rule of using a yard trimmer is to use only monofilament line specified by the manufacturer of your trimmer. Make sure it is of the same size and stiffness.

What Can Go Wrong with a Yard Trimmer?

Yard Trimmer Repair

Components of a typical gas-powered yard trimmer.

The most common problem with a string trimmer is that the unit runs out of string. The string may also be twisted or loose on the spool. The cutting head may be dirty or the head outlet guide may be bent. An electric trimmer’s power cord, switch, or motor may fail. A gas trimmer’s engine may be faulty. The air filter or exhaust port may be blocked. The trimmer may need lubrication and cooling fins or air passages may be blocked. A cordless trimmer’s battery or charger may be faulty.

How Can I Identify a Yard Trimmer Problem?

  • If a yard trimmer doesn’t cut, refill the monofilament line spool or replace the blades (see below). Inspect the cutting head and replace any damaged parts.
  • If yard trimmer line doesn’t advance or breaks during use, rewind loose line on the spool, clean a dirty cutting head, reshape a bent head outlet guide with pliers and smooth the edges with sandpaper. As needed, replace a badly damaged head (see steps 1 through 3 of Install monofilament line below).
  • If an electric yard trimmer doesn’t operate, make sure power is on at the electrical receptacle, and test the electrical cordswitch, and motor.
  • If an electric yard trimmer lacks power or overheats, make sure you are using an outdoor extension with the proper capacity for the trimmer (check your owner’s manual). As needed, test the motor.
  • If a gas yard trimmer doesn’t work, first check the owner’s manual to make sure all controls are set properly. Check the small engine that powers the unit.
  • If a gas yard trimmer stalls or runs intermittently, check the fuel lines for blockage and check the air filter or exhaust port for blockage. Check the small engine that powers the unit.
  • If a gas yard trimmer overheats, check your owner’s manual for lubrication points on the unit’s small engine and remove any debris that may be blocking the cooling fins or air passages.
  • If a cordless yard trimmer doesn’t work, check its battery and battery recharger.


Always inspect the yard trimmer before each use. Cracked or damaged parts can shatter and cause personal injury. And always wear eye goggles to protect your eyes.

What Do I Need for Yard Trimmer Repair?

Replacement parts are available from lawn equipment suppliers and the manufacturer. Most hardware stores and home improvement centers have a supply of monofilament line and common replacement heads. The tools you will need to fix a yard trimmer include these:

  • Screwdrivers
  • Wrenches
  • Multimeter

What Are the Steps to Yard Trimmer Repair?

Access yard trimmer components:

  1. Remove all housing screws and place them in a container for easier reinstallation.
  2. Dismantle the housing, making sure you don’t lose any parts.
  3. Remove the trigger and other internal parts to check for wear and replace as needed. Heavy-duty trimmers will include a filter and other components.

Install yard trimmer monofilament line:

  1. Press the locking tab on the side of the spool as you rotate the locking ring in the direction of marking arrows.
  2. Remove the locking ring and inspect it, replacing it if damaged.
  3. Remove the automatic-feed (or tap) button and inspect it for cracks or other damage, replacing as needed. Clean debris from around the button.
  4. Remove the spool and slide it from the hub. Be careful because some models include a spring underneath that can fly off and easily get lost.
  5. Wind new monofilament line on to the old spool or replace with a pre-wound spool. If your yard trimmer has blades instead, check them for damage and replace as needed.
  6. Insert the end of the line through the spool hole and wind the line in the direction of the arrow.
  7. Reinstall the spool and test the unit.


Some yard trimmers come with or have been retrofitted by the owner with plastic blades replacing the monofilament line and heads. Make sure that the blades are firmly attached and in good condition before operation. Getting hit with a chunk of plastic will hurt more than with a mono line.