Here is the info from the manual, the replacement line is put in near the center of the spool on the top of it, you simply feed it in. I have included a link to the manual so you can see the pictures. Look at page 10 for these instructions.
Pre--wound spools offer the most convenient
method for replacing line and ensuring optimum performance.
S Replacement spools are color--coded to ensure use of the correct spool with your unit.
Be sure to use the same color spool as the
NOTE: Always clear dirt and debris from
cutting head components when performing
any type of maintenance.
S Hold spool and unscrew cap by turning in the
direction shown on top of the cap.
S Remove line guide ring and spool.
NOTE:When removing and/or installing spool,
ensure dust cup remains installed over shaft.
Use a pre--wound spool or refill spool with
line. If using a pre--wound spool, remove tape
strip from line and spool.
REFILLING THE SPOOL WITH LINE
WARNING: Use only 0.080" (2 mm)
diameter round line. Other sizes and shapes
of line will not advance properly and will result in
improper cutting head function or can cause serious injury. Do not use other materials such as
wire, string, rope, etc. Wire can break off during
cutting and become a dangerous missile that
can cause serious injury.
1. Cut a length of 25 feet of 0.080" (2 mm) diameter round WEED EATER brand line.
Feed line in
2. Insert one end of line into center cavity of
empty spool. Ensure line will feed into
spool in the direction shown on the spool
3. Continue feeding line into spool, leaving 4 --
6 inches (10 -- 15 cm) unwound from center