Sometimes the line around the spool could melt together. This condition results from ultrasonic resonance of the line within the spool. It can happen with any type of line, but is more prevalent with round shaped line than with square or hexagonal line.

Line melting (line welding) can occur when trimming continuously at high speed against hard, stationary objects such as fences, curbs, or walls.
It can also result from excessive twisting of the trimmer line during installation.
To reduce the risk of line welding:
1. Use a lower trimmer head speed when trimming near hard objects, and vary the throttle speed during operation.
2. When winding the trimmer line onto the spool, allow the line to hang freely and rotate the spool around the line. Avoid holding the spool stationary and wrapping the line around it, as this can twist the line and cause it to bind or fuse together during operation.
3. Remove any melted or fused trimmer line and replace it with a new line that meets the specifications in your product's operator's manual.
