Fix it
String Trimmer Not Working? Fixes
Common battery string trimmer problems and fixes: line not feeding, weak cutting, and power issues.
Most trimmer problems trace to three things: the line, the battery, or debris in the head. Work through these fixes before assuming the tool is broken.
Line will not feed
On bump-feed heads, line welds to itself inside the spool when it gets hot; open the head, separate the coils, and rewind neatly. On automatic heads, check that the line is threaded through the eyelets correctly and that you are using the diameter the head is rated for.
Trimmer bogs down in grass
Let the head reach full speed before entering the grass, and take narrower bites in thick growth. If it still bogs, the battery may be low; voltage sag under load is the most common cause of weak cutting on a tool that worked fine last week.
Battery dies quickly
Small amp-hour batteries drain fast under trimmer load; switch to a 4.0Ah or larger pack. Also check the Power Command or speed dial: running at full speed in light grass wastes charge for no benefit.
Excessive vibration
Stop and inspect the head: a broken or unevenly worn line throws the head off balance. Replace the line, clear wrapped grass from the head, and check that the guard is firmly attached.
Questions, answered
Why does my line keep breaking?
Three usual causes: line thinner than the job needs, cutting against concrete or fences, or old line that has dried out and gone brittle. Fresh line of the correct diameter fixes most cases.
The trimmer runs but will not cut. What now?
Check that line is actually extending from the head; a spool can run empty while the motor spins fine. If line is present but short, advance it per your feed system and confirm the head is not clogged with wrapped grass.