For tuners I use a wax-based lubricant, such as old-fashioned Chap Stick. Very little. A slight film is all that is necessary. After application, rotate the tuner a complete revolution of the tuner post to make sure it is evenly distributed. I took grief in another thread for advising against any oil-based lubricant, because it can seep into the wood and cause deterioration. But I stand by that post. Will it? Just like those who insist on using long-scale strings on short scale basses with the ill-advised justification, "Well, the E string has never snapped on me (yet)," why take the chance because when it does, you can't fix it. If you look at ancient Kluson tuners with a small hole in the casing, they used a solid lubricant, not oil. From another forum, this quote from Kluson, "This is a lubrication port. We recommend a grease for gears and not an oil or WD-40 as it will leak out through the housing seams and make a mess." This post followed a discussion that tuners really aren't meant to be lubricated, unless there is a severe sticking or hanging issue, as the OP sets forth. If the tuner still sticks, then if it is a traditional open tuner, take it apart and try to find the burr or miscut in either the gear or the worm and fix it.
