"It will not stay in tune" is four different faults wearing the same coat. The good news is that they drift in distinguishable ways, and that three of the four are fixed by things costing less than a set of strings.
The bad news is that the fourth — a badly cut nut — is bench work. So the first job is telling them apart.
Match the pattern to the cause
Everything goes flat, steadily, for the first week. New strings settling. Normal, temporary, and not a fault. It ends.
One string drops suddenly, always the same one. The winding at the post is slipping. That is a technique problem at the last string change, not a hardware fault.
A string pings when you tune, then reads sharp. Friction: the string is binding in the nut slot, releasing all at once. Classic on the G and B of an acoustic, and on any guitar after a bend.
It goes sharp only with a capo on. Capo pressure or placement, not the guitar — how to use a capo covers both.
It drifts when the room changes. Wood and steel move with temperature and humidity. A guitar carried in from a cold car will not settle for a while.
Every string change
How often MusicNomad says to apply nut and saddle lubricant
It is the only maintenance interval published in this whole problem area, and it targets the one cause most players never think to check: friction where the string crosses the nut.
The five causes, and what each is worth spending on
1. New strings that have not settled
Every set stretches. Tune up, play, retune, repeat — over a few days the drift stops. D'Addario's own stretching advice adds the one caution worth repeating: do not overdo it, or you can break strings. How to change guitar strings covers the routine.
Spend nothing. This one is time.
2. String ends wound badly at the post
Too few turns and the string slips; too many and they climb over each other and creep. Neat, downward turns with the string locked under itself hold. A winder with a built-in cutter makes the job quick enough that you do it properly.
Spend a little. A pro-style winder pays for itself in restrings, and the winder roundup compares the options on published specs.
3. Friction at the nut, saddle and string trees
This is the cause most people never check. The string does not glide through the nut slot; it grips, tension builds behind it, then it releases with an audible ping and lands sharp. MusicNomad sells TUNE-IT precisely for this and publishes where it goes — nut slots, saddles, string guides, every point the string passes over — and how often: every string change.
It also publishes a warning worth reading before you apply it anywhere: do not put it on tuning machine eyelets, because that is an anchor point and slipping there is the opposite of what you want.
Spend a little. This is the cheapest real fix in the list.
4. A nut slot that is cut wrong
Lubricant helps a slot that grips. It does nothing for a slot that is too narrow, too tight at the back, or cut at the wrong angle. If a string still pings and jumps after lubrication, that is bench work — and does my guitar need a setup sets out what a technician does and what it is worth.
5. The room
Taylor publishes a target range of 40% to 60% relative humidity for its guitars. Outside that, wood moves, and a moving neck moves tuning with it. A hygrometer answers this for the price of a couple of picks — guitar hygrometers covers what the makers publish for accuracy.
What to check, in order
Symptom, cause and the cheapest fix| What you hear | Likely cause | Fix | Cost |
|---|
| Everything flat for days | New strings settling | Play and retune; stretch gently | Nothing |
| One string drops suddenly | Slipping winding at the post | Rewind it properly | Nothing, or a winder |
| Ping, then sharp | Binding in the nut slot | Nut and saddle lubricant | Low |
| Still pinging after lubricant | Nut slot cut wrong | Technician | Bench rate |
| Sharp only with a capo | Capo pressure or placement | Move it behind the fret; less pressure | Nothing |
| Drifts with the weather | Humidity or temperature swing | Hygrometer, then humidity control | Low |
The picks
MusicNomad TUNE-IT — best fix for a sticking nut
A PTFE-fortified gel with a fine applicator, aimed at exactly the contact points where tuning stability is lost. MusicNomad publishes the application points, the interval, and the one place not to use it. It also states it does not affect the sound or sustain of the strings.
Against it: no volume published on the maker's own page, it may slightly color a wooden nut, and it cannot rescue a badly cut slot.
Korg Pitchclip 2 — best tuner to diagnose with
You cannot diagnose drift you cannot see. The Pitchclip 2 publishes ±1 cent accuracy and around 24 hours of battery, which is enough resolution to watch a string creep and enough runtime to leave it clipped on.
Against it: a clip-on reads the whole instrument's vibration, so it is less precise than a strobe for fine work, and it needs the room reasonably quiet.
D'Addario Pro-Winder — best for winding strings properly
The winding at the post is the cause people least suspect and most often have. A winder with an integrated cutter and bridge-pin puller makes a tidy restring quick, which is how the winding stops slipping.
Against it: it fixes the cause only if you use it to wind neatly — the tool does not make the turns for you.
Elixir Phosphor Bronze NANOWEB — best strings to stop blaming
If your strings are old, every diagnosis above is contaminated. A coated set stays serviceable longer, which removes the variable for months at a time rather than weeks.
Against it: coated strings cost several times a plain set, the feel is different, and they still stretch in like any other new string.
Things that are not the problem
Cheap tuning machines, usually. They get blamed far more often than they fail. Slipping at the post looks identical from the player's seat, and it is free to fix.
The tuner being wrong. If two tuners agree and the guitar still drifts, the guitar is drifting.
Intonation. A guitar that holds its pitch perfectly well but sounds sour on chords up the neck has the opposite fault, and it is set at the saddle rather than the nut — guitar intonation covers the check and which way the saddle moves.
A string that snaps rather than drifting. That is a mechanical failure with its own causes, most of them at the bridge saddle or the nut — why strings keep breaking reads the break location.
Needing a setup, immediately. A setup is worth paying for when the nut or the neck is genuinely out. Try the free causes first — they cover most cases.
What we would actually buy
If a string pings and lands sharp: TUNE-IT, applied at the next string change. If you cannot tell what is drifting: a clip-on tuner you can leave on the headstock. If a single string keeps dropping: nothing — rewind it, with a winder if restringing is a chore. And if the strings on the guitar are older than you can remember, start there.
What we did not doWe have not played any of this gear. Every guide in this category says it tested twenty tuners; we would rather say plainly that we tested none. What we did instead is on this page in full: published specifications with their sources, the makers' own manuals read rather than paraphrased, and a note wherever a company publishes nothing at all.
