Operating; Cutting Instructions; To Turn The Tool On; Replacing Line On A Spool - EarthWise ST00009 Operator's Manual

Before you start the unit, make sure the trimmer is not
contacting any object.
Squeeze the trigger with your fingers. To turn the tool
OFF, release the trigger.
Firmly push the tabs on both sides of the hub to release it
and remove along with the spool from the cutting head.
Position hub over spring and align tabs with rectangular openings.
Press firmly on tabs and push until hub snaps into place.
TAB
Firmly push the tabs on both sides of the hub to release it
and remove along with the spool from the cutting head.