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How to Replace Trimmer Line

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Whether you’re working with a commercial string trimmer or a regular model you shouldn’t find it too hard to replace trimmer line. Replacing line is more fiddly than difficult, but some people become frustrated by them, especially when they are working on their own.

How to Replace Trimmer Line

Read your manual so you can be sure that you fit the right size cord. This will also help you get to know the various parts of your machine. It’s also vital to ensure your safety. The trimmer should be undoubtedly switched off; otherwise, you can be seriously hurt. Engineers recommend that the gearbox should have been allowed to cool before replacing the cord.

Make sure that you have a suitable working space and that you know where the various parts have been put down because it is incredibly easy to lose the spring! As well as a generous workspace, you’ll need to have a sharp cutting tool as you do not want a frayed or badly cut cord.

Single Line Trimmer

1: Take the spool and cut the piece of line that you want to fit. Follow the manufacturer’s guidelines as to length. It should be at least ten feet, and it pays to have a measuring device with you.

2: Then, take off the trimmer’s head. To do this unscrew the retaining cap. You generally have to press one or two tabs, as you do on bleach bottles, at the same time. Remove and straight away discard the old cord to keep your workspace tidy. Place the retaining cap on your workbench to prevent it from getting mislaid. If you are replacing the cord while in the garden, make sure that you keep all tools and bits together in one place. You will not regret doing so!

3: Find the starter hole in the spool and carefully thread the new spool line through it. Then you have to begin winding. It is essential to say that neatness matters here, as an untidily wound line will soon cause you problems and is likely to snag or jam. Wind it as though you were winding a fishing line. As well as having to be tidy, you will have to hold your line firmly. Otherwise, it will loosen. You should have about six inches of cord left unwound. This is your cutting edge.

4: You will then notice two slots, one in the head and the other outside the head. The smaller one, which is in the head, is known as the retainer slot, which fixes the cord in place while you are refitting the head. Fix the part of the cord still unwound into the retainer slot while you replace the head.

5: To this line up the two slots. Then you place the spring followed by the head. Pull the cord firmly into the lower slot. While holding down the head, replace and screw in the retaining cap.

Two Line Trimmer

Steps 1-3 are the same as above.

4: There are two starter holes, each of which has to have a cord around it so you will need to cut two pieces of cord. There are also two retaining holes. Deal with each as you would if you were winding a single line trimmer. Whichever you do first, ensure that the cord is retained wound and retained adequately before you move on to the next one.

5: As with step 5 above, except some trimmers have eyelets. Others have slots. Line them up with the retaining slot and thread the cords through them. Ensure that both lengths are even, wind by twisting the head clockwise until six inches get exposed on each side.

Speed Feed Trimmer

Steps 1 and 2 are as above.

3: You will see eyelets and arrows. Rotate the cap until eyelets and arrows align. To test if the alignment is exact look through, and if you can see daylight, the alignment is right. Thread the line through an eyelet and out through the other. Pull each cord until the same length protrudes on each side.

4: Wind by rotating the trimmer head clockwise until 6 inches shows on each side.

If you’re still having difficulty check the video out below:


  1. Royal Horticultural Society Encyclopaedia of Gardening, Ed: Christopher Brickell, 2002

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