Weed Eater trimmer line is made of sturdy plastic, but it can break if you hold the trimmer head too close to hard objects like fencing, rocks or concrete while you're edging your lawn. Luckily, if your line breaks you can re-thread it yourself without any special tools. Spools of trimmer line are available in hardware or home improvement stores. There are even pre-cut line replacements for some trimmer models. Weed Eater is a trademarked brand of weed trimmer, but the same re-threading process works with any brand of trimmer.
Identify the correct size trimmer line for your model. Find this in your user manual, or take a piece of your line to a home improvement center and locate the same line. There are three standard thicknesses: .065, .080 and .095.
Remove the retaining ring cover from your trimmer head. There are three ways a retaining ring could be attached, so your Weed Eater will use one of the following. Either press a tab on the retaining ring to release it, unscrew the retaining ring from the trimmer head, or press a tab and unscrew the retaining ring.
Remove the spool from the trimmer head and pull out the broken line. There will either be one or two holes in the spool, depending on whether your model uses one or two lines.
Cut 15 to 25 feet of new replacement line from the spool you just bought. Regular scissors will cut through it. If you bought pre-cut line, you won't need to measure or cut.
Thread the new line into the hole in the spool. If there are two holes, cut a second piece of line the same length as the first and insert one into each hole.
Wind the line around the spool in the direction indicated on the spool. There's always an arrow on the spool showing you which way to wrap the line.
Put the spool back in the head and thread the line or lines through the eyelet on the side of the trimmer head.
Replace the retaining ring cover the same way you took it off.