Twist the spool cover, located on the bottom of the Husqvarna weed trimmer, counterclockwise and lift up. The cover containing the spool holder should lift off the center notch holding it in place on the base.
Pull the spool cover up and off the plastic spool holder container the weed trimmer line. Remove any remaining line left on the holder.
Pull off approximately 6 to 8 feet of new line. Cut the line off using scissors or a utility knife.
Thread the new line through the two notches located in the center section of the spool holder. Pull the line through the notches until one line is approximately 5 inches longer than the other line.
Grab the spool holder with one hand and hold the two lines together with the other. Separate the two lines with the tip of your index finger. Wrap the line tightly around the center section of the holder, wrapping clockwise.
Stop wrapping the line when there is approximately 8 inches left. Insert each line end through one of the two holes located on the holder's top edge. Pull the line taut.
Thread the lines through the two holes located on the spool cover's sides. Slip the cover over the line and onto the holder, pulling the lines through the holes. Push down until the spool holder is in place inside the spool cover.
Push the spool cover down on the center notch on the weed trimmer's base. Push down until it clicks securely in place. Start the Husqvarna weed trimmer to trim off any excess line.