How do you replace string?

SOURCE: How do you Replace string on the trimmer head spool

Take the spool off and turn it up side down take out the centre and wind the left side 6 times to the left and the right side 6 turns to the right then put the ends through the holes and refit to stud and screw on butter fly nut...
Dont try winding them both the same way as when you try to get more out 1 side will come out and the other will go inside so you will be back were you started

SOURCE: The string on my spool ran out.

• Turn off the trimmer and remove the battery
• Press the release tabs on the line spool cover and remove the cover by pulling it straight off. replacement spool is AF-100
• Lift the spool of nylon line out of the hub and clear any broken line and debris
• In case of jams and tangled line unwrap about one foot (30cm) of line to ensure that it is undamaged. If it is OK rewind it and insert the line end through the eyelet in the spool hub.
• Pull the line through the hole to maintain tension while placing the
spool down into the hub with the notched side exposed.
• Press the spool down GENTLY and rotate it until you feel it drop into place. (When in place, the spool will turn a few degrees left and right freely.)
• Snap the spool cover back on.

SOURCE: How do you put new

The spools are replaced with fresh ones.