Guitar tuning machines, especially those with open tuners, contain gears that will wear as time goes by. Therefore, they need some simple maintenance from time to time to make sure they function well. As long as you keep your gears free of debris and lightly lubricated, they should last for many years.
Place a small amount of high-viscosity bicycle chain oil on a toothbrush, toothpick, or cotton swab and apply it to the mechanism/gear. Turn the tuning peg back and forth a few times to spread the oil throughout the mechanism. Finally, wipe any excess oil off the surfaces of the gears.
The small amount of oil that is left on the parts is all that is needed to ensure efficient tuning. Don't over-lubricate guitar tuning pegs and never lubricate with low-viscosity oil, it will wick behind the plates and damage the wood and finish.
