Guitar Keeps Going Out of Tune — What to Do?
Common causes include new or old strings, cheap tuning machines, or a binding nut. After fitting new strings, gently stretch them several times by hand so they settle. Rub the nut slots with a soft pencil (graphite acts as a lubricant). Tune the guitar daily and play it in — after 3–5 days the tuning should hold noticeably better. Loose or wobbly tuning pegs can only be fixed by replacing them with better tuning machines, which a guitar technician can do.