Things You'll Need
Replacement parts (as needed)
The automatic feeding system on a Weed Eater is designed to force more line out when it's needed. Depending on the model, this occurs when either the head is tapped or the line gets too low and the centrifugal force pushes the line out. In either case, the basic operating systems are the same. Most of the time, when the feeding system isn't working, a jam or clog is blocking the line from exiting. Clearing away this jam and check the feeding system for damage will help solve most automatic feed problems.
Set the Weed Eater atop a workbench so the head's bottom is facing up. Press down on the center knob and twist it slightly. Pull up on the knob to take the spool out of the head.
Unwind any string still left on the spool. Check the string for crisscrossing and overlaps, as this will stop the automatic feed system from working. Wipe the spool and inside the Weed Eater's head with the rag. Check the spool for any cracks, holes or other damage. If the spool is damaged it won't spin inside the head and the feeding system will stop working.
Pull the spool retainer, a metal clasp at the center of the head, out of the head with the needle-nosed pliers. Slide the return spring out of the head's center. Check the spool retainer for signs of damage. Replace if it's cracked, bent or broken. Replace the spring if the ends are bent, the spring has lost its elasticity or is damaged in any way.
Reassemble the head parts in reverse order. Set the spring onto the center. Push the retainer into the center. Rewind the cutting string around the spool, keeping the line tight and the rows even. Fit the spool back into the head. If the automatic feed still isn't working, repeat these disassembly steps and remove and replace the entire cutting head.