Because there are many variables when it comes to tuning problems, it’s not terribly helpful to give your guitar to a tech and say, “It won’t stay in tune.” Having a think about some stuff beforehand can make a good result more likely.
So, I want to talk about a few tips related to string ‘break angle’ — the angle the string takes over the nut or saddle. However, I reckon that it might be useful to explain what I mean and to give a little background on this area first.
Let's start with the break angle at the nut — that's the angle at which the string leaves the nut and heads for the tuner.
Removing a tuner bushing from a guitar headstock can take a hunk of lacquer with it.
Same applies to those little ferrules on the back of your Tele, or those big ferrules on the back of your bass. Or anything else that has little or big ferrules or bushings. The lacquer can adhere to the bushing and when you remove it some of the lacquer comes too. Grrrr!
The trick is to get the lacquer to let go.
Do that by heating the bushing. Just hold a soldering iron against it. You don't want it to be red hot or anything, but a bit of heat evenly through the bushing will soften the lacquer under it. This makes it a safer job to remove the bushing.
Out and safe.
Good for installing too
By the way, this also works when you're installing new bushings or ferrules. Heating them as they're pressed in can soften the finish and help prevent is chipping as the new hardware is forced in.
If your headstock looks like this, it's probably an indication that something's gone wrong along the way.
The previous owner of this bass had left the current owner with some very badly fitting tuners. There was a heap of wood gouged out to try fit some locating keys on a set of tuners and the shaft holes had been badly enlarged and were weird egg shapes (as well as being a poor fit for the tuner bushings).
After I'd trued up the shaft holes, they were far too big. The solution was to turn down a square-cut piece of maple in a lathe until it was a nice, snug fit for my round hole.
That's how you fit a square peg in a round hole.