How to Unfreeze a Bump Knob From a Troy Bilt Weed Trimmer

Unplug the wire from the spark plug on your Troy-Bilt weed trimmer. Place the weed trimmer on its side.

Hold the outside of the spool housing with one hand and twist the bump knob clockwise with your free hand. If necessary, turn the bump knob initially with pliers if it is difficult to turn by hand.

Pull the inner spool out of the outer housing with your fingers. Look for a spring on the top of the spool. Inspect the spring for damage. If the spring is bent, purchase a replacement at a home improvement center.

Hold the bump knob with one hand and turn the bolt on the top of the knob with your free hand. The bolt should turn freely inside the knob. If it does not, look for cracks or damage on the knob. If you find damage replace the knob.

Spray inside the hole where the bolt threads exit the bump knob with silicone, if there is no damage. Turn the bolt left and right to distribute the silicone.

Apply a thin film of petroleum jelly onto the center shaft of the outer housing with your fingers. Clean the inside of the outer housing with a rag to remove any caked-on dirt or grass.

Place the spring over the center shaft of the outer housing and insert the inner spool over the spring with the ends of the line going through the eye holes of the outer housing.

Thread the bump knob onto the trimmer counterclockwise until it is hand tight. Push the end of the plug wire over the spark plug.