Why won't my instrument stay in tune?

When an instrument goes out of tune, the tuners aren't necessarily to blame. Common causes are new strings that haven't settled, poor winding on the posts, friction in the nut and how the bridge behaves.

If you hear a small "ping" and the note jumps, the string may be sticking in the nut slot. If the problem shows up after using the tremolo, the system needs checking to see whether it returns to its resting position.

Sudden temperature changes play a part too. Notice when the problem happens and on which strings. If the open strings stay in tune but fretted notes sound wrong, check the intonation before assuming the tuning itself is unstable.