Before replacing your weedeater's line, it is helpful to familiarize yourself with its operating mechanism. Most weedeaters are composed of three main parts: the mower, the connector and the engine. Connected to the bottom of the engine is the trimmer which spins the cutting line at high speed. These instructions will tell you how to replace the cutting line on most models of weedeater. However, it is only meant to be a supplementary guide. Your weedeater's owner's manual will contain specific instructions for your particular model.
Cut off the weedeater's power source (for most models, this is as simple as unplugging it). Then try to engage the cutter to make sure that it will not turn on while you are using it.
Turn the mower upside down so that the cutter is facing you.
Remove the trimmer head spool from its housing. For most models, this is accomplished by twisting the spool counterclockwise and pulling it out. Other models have flip or push locking mechanisms. To locate these, consult your owner's manual.
Remove the old weedeater line and any grass or debris from the spool and the whipping chamber.
Double the replacement weedeater line so that you have two equal pieces of equal length.
Bend two inches of one end of the replacement weedeater lines at a right angle.
Feed one of the bent weedeater lines into the internal locking device in top groove of the spool. On most models, the internal locking device is a slot or hole in the grooves of the spoon. Feed the other bent end of the weedeater line into the bottom groove of the spool.
Loop both weedeater lines around the spool in the direction indicated on the top of the trimmer head spool.
When there are roughly 7 inches of weedeater line left, insert those ends into each of the grooves or slats on opposite ends of the top surface of the trimmerhead spool.
Replace the trimmer head spool into the spool housing using the opposite of the method you used in step 3. As you replace the trimmerhead spool, thread each of the weedeater lines thorough each of the holes in the spool's housing.
Take an end of the weedeater line in each hand. Then pull them out simultaneously until they lock in place.