Weed Eater shafts require very little maintenance overall. Unless the owner specifically looks for the actual drive shaft, he would not realize it even existed. The rigid tubing running from the drive motor to the trimmer head houses a small spiral shaft. It is made of several twisted wires, making it possible to transmit torque while remaining flexible. Lubrication of the shaft reduces friction and wear created by it rotating inside the outer housing. It also serves as a corrosion inhibitor and water repellent should the Weed Eater be exposed to moisture.
Remove the trimmer shaft from the motor. Four to six screws secure the shaft housing to the motor assembly. Back the screws out with a Phillips-head screwdriver and slide the shaft away from the motor. Placing the trimmer on a clean concrete surface provides an excellent work area for this job.
Pull the drive shaft out of the housing by hand. Slightly turning the shaft as it is moving out will overcome any resistance. Wear gloves and have a few shop rags available during this phase of the job.
Spray the shaft down with a light oil if it appears contaminated with dirt or corrosion. Wipe it down with a clean rag after coating it with the light oil.
Coat the entire shaft with the manufacturer's recommended shaft lubricant. Shaft lubricant is specially formulated grease or oil which provides the best overall protection of the shaft. The lube is available in the parts area of most home and garden supply stores.
Slide the shaft back into the housing. Slightly twist the shaft while pushing it in to overcome any friction. Ensure the end of the shaft inserts into the trimmer head drive--twisting the shaft by hand or with a pair of pliers should turn the trimmer head.
Reinstall the shaft assembly onto the motor and insert the screws using the Phillips-head screwdriver.