How to Restring a Weed Eater: Step-by-Step Guide

Trimmer line runs out during use, and loading a fresh spool is a routine maintenance task every string trimmer owner needs to do periodically. The procedure is straightforward once the winding direction and anchor method of the specific head are understood, but getting those two details wrong produces a spool that jams immediately or fails to feed line correctly. This guide covers the restringing process for the most common residential trimmer head type: the bump-feed head used on gas, battery, and corded electric trimmers from most major brands.

Understanding Bump-Feed and Fixed-Line Heads

Bump-feed heads contain a spool of pre-wound line that advances a short length of fresh line each time the bump knob at the base of the head is tapped against the ground during operation. A spring-loaded mechanism in the head releases a measured length of line with each bump. When the spool runs out, the head is opened, the empty spool is replaced or reloaded with new line, and the head is reassembled.

Fixed-line heads do not contain a spool. Instead, short pre-cut lengths of line are inserted into holes in the head directly. When those lengths wear down, the head is stopped and the worn lengths are pulled out and replaced with fresh pre-cut pieces. Restringing a fixed-line head means removing worn stubs and inserting fresh cut lengths into the corresponding holes, which is simpler than spool winding but requires keeping pre-cut line lengths on hand.

The steps below apply to bump-feed heads, which are by far the more common type on residential trimmers.

What You Need

New trimmer line in the correct diameter for the head is the only material required. The correct diameter is listed in the owner’s manual and is often marked on the spool or bump knob. Most residential bump-feed heads use 0.065 to 0.080 inch diameter round line. Using a heavier diameter than the head is rated for causes the line to bind inside the spool cavity and prevents the bump-feed from working. The best trimmer line guide covers diameter, shape, and material selection in detail.

The Winding Direction

The most common restringing error is winding the line in the wrong direction on the spool. When wound backward, the bump-feed mechanism advances the line the wrong way and jams the spool against the housing instead of releasing it. The correct winding direction is printed on the spool as an arrow labeled “Wind” or indicated by an arrow embossed on the spool surface. On most heads, looking at the bottom of the head (the bump knob side), the line winds counterclockwise. Always check the specific spool before winding.

Step-by-Step Restringing

Follow the HowTo steps above for the complete procedure. The key points that most commonly cause problems are the following.

Keeping the wound line tight and in even, non-crossing layers prevents the inner layers from collapsing under the tension of the outer layers and jamming the spool during use. Slack winding produces a loose spool that jams after the first bump.

Seating the free line ends in the retaining notches on the spool rim before reassembly prevents the line from slipping back into the housing during reassembly and requiring the head to be disassembled again to re-route the ends.

Routing the line ends through the exit eyelets in the housing before pressing the spool down is easier when the head is held upright with the bump knob facing down. Gravity keeps the spool seated while both line ends are routed.

Line Jams: Causes and Solutions

A line jam occurs when the spool binds inside the head housing and the bump-feed mechanism cannot advance the line. Common causes include line wound in the wrong direction, lines that have crossed inside the spool during winding, a line diameter heavier than the head’s rating, or old brittle line that has fused to itself during storage. To clear a jam, remove the head cover, lift the spool, manually pull a length of fresh line free, and reseat the spool while keeping the line routes clear of the spool rim.

Pre-wound Replacement Spools

Some trimmer brands sell pre-wound replacement spools as an alternative to field restringing from bulk line. Dropping in a pre-wound spool is faster than winding from a bulk roll and eliminates the winding direction step entirely. The trade-off is higher cost per foot of line compared to bulk line on a 50-foot or 100-foot roll. Pre-wound spools suit buyers who value convenience and trim infrequently enough that the cost per replacement is not significant over a season.