Tuning pegs are responsible for tuning and holding string tension and are the hardest working part on a guitar. Being the instrument's only moving part, they are susceptible to wear and require eventual replacement. Tuning pegs are also a popular aftermarket upgrade, allowing players to inexpensively improve tuning stability and performance. Called machine heads, tuners, tuning keys or tuning pegs, parts companies manufacture replacement tuners for most every instrument. Even if your brand cannot be found, suitable replacements can be fitted with a minimum of hassle.
Loosen and remove strings by turning the tuning pegs clockwise with a peg winder or fingers.
Remove the screws from the tuner assembly on the back of the headstock with a small flat head or Phillips screwdriver.
Identify the bushing surround the tuning post by viewing it from the top of the headstock. A hexagon shape indicates a threaded bushing, and a circular shape indicates a pressure-mounted bushing.
Remove threaded bushings by turning counterclockwise with an adjustable wrench. The tuners will easily push out from the top.
Remove pressure bushings by first pushing the tuners out through the headstock and inserting a flat head screwdriver through the back of the hole, popping the bushings out with a little pressure.
Measure the centres of each hole to the next hole if the guitar is equipped with three or six inline tuners. If replacing individual tuners, measuring is not necessary.
Take the guitar and old tuners to a music store to ensure an exact replacement fit, or relay measurements and model information to your online retailer.
Press new tuners through the headstock tuner holes and line up with screw holes.
Tighten the screws with a Phillips or flat head screwdriver. If screw holes have become stripped, they can be filled with a piece of toothpick coated in wood glue before new screws are inserted.
Replace bushings by pressing in pressure-mounted bushings with fingers. Screw threaded bushings with fingers in a clockwise direction, with final tightening done with an adjustable wrench.
Re-tighten retaining screws and bushings.
Restring guitar and tune to pitch.
Some tuners have adjustment screws on the tip of the tuning peg. Check the adjustment of this screw, which adjusts the action of the turn-peg. It should be firm, but not overtightened. Open-back tuners can be lubricated periodically with a dab of petroleum jelly. Choose tuners that will fit your guitar to avoid extra guitar repair shop fees. Although widening of shaft holes is a fairly inexpensive modification, choosing tuners with too small a shaft should be avoided.
New holes, or widening of old ones, to accommodate non-standard tuners should be done by a professional guitar repair shop. Don't leave guitar without strings for long periods, because neck problems may develop due to tension loss. Chock the neck up underneath the guitar's nut with a styrofoam block or sturdy box, and avoid putting excess pressure on the neck and headstock, which may result in catastrophic damage or expensive crack repairs.