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How to Refill an Echo SRM231 String Trimmer

By James Young ; Updated September 21, 2017

The Echo SRM-231 feeds two cutting lines through an automatic advance trimmer head which stores the trimmer string itself in one spool compartment. To properly feed the line through the head, both trimmer lines must be wound neatly and separately on two halves of the same spool. Any overlaps or crossing of the two lines causes the mechanism to jam. Even with practice rewinding the Echo SRM-231 spool can be difficult and frustrating.

Replacing Line

Grip the drum or outer housing of the trimmer head with the left hand. Turn the inner spool clockwise until it stops. Do not push the spool in as it turns. Pull the spool out of the trimmer head and clear of the shaft.

Use the needlenose pliers to pull any old line out of the spool. Be careful not to damage the plastic loop which anchors line to the hub of the spool.

Thread one end of the 40-foot strand of trimmer line through the anchor loop in the center of the spool. Pull the line through until one side of the doubled strand measures six inches longer than the other side. Hold the spool in the left hand socket side down and drape both ends of the line to the right.

Hold both strands in the right hand, letting them slide through your fingers as you turn the spool counterclockwise with the left hand. Place the tip of your right index finger on the hub of the spool as you wind the line to keep the two strands separated and tight.

Wind the spool until the two coils meet in the center of the hub and then guide them into another layer of winding. The two sides of the cutting line must be wound tightly and neatly without overwrappping and without crossing. Continue spooling the line until the free length of the shortest strand measures six to eight inches.

Lock the short strand in one of the two notches on the inside or bottom flange of the spool. Friction should hold it securely in place. Wind the second strand until only six to eight inches of free length remains and lock this line in the second notch, on the opposite side of the flange.

Feed each line through one of the trimmer line ports in the drum of the trimmer head. Line up the spool with the driveshaft until the pegs on the shaft match the notches on the spool. Push the spool firmly onto the shaft.

Pull the end of each line tight to free the cutting line from the notches on the spool. Turn the spool counterclockwise, without pushing in, until the spool stops turning. Trim the two cutting lines to equal length with the wire cutter jaws of the pliers.


Things You Will Need

  • 40 feet of Echo 0.096 inch diameter cutting line
  • Needlenose pliers
  • Echo SRM-231 Line Trimmer


  • Rapid loader replacement heads substitute for the SRM-231's original manual-loading dual line spool.

About the Author


James Young began writing in 1969 as a military journalist combat correspondent in Vietnam. Young's articles have been published in "Tai Chi Magazine," "Seattle Post-Intelligencer," Sonar 4 ezine, "Stars & Stripes" and "Fine Woodworking." He has worked as a foundryman, woodturner, electronics technician, herb farmer and woodcarver. Young graduated from North Seattle Community College with an associate degree in applied science and electronic technology.