Locking guitar tuners, which are designed to eliminate the string slippage that has typically plagues guitarists, have become increasingly popular over the years, and most high-end guitars include locking tuners as a standard feature. Sperzel locking turners use a unique locking method in which a "locking pin" mounted inside the tuning post captures the string and holds it tightly in place while the string is tuned. Installing Sperzel tuners requires some modifications to the headstock of the guitar and should only be attempted by guitar owners who have some confidence in their ability to perform these modifications without damage to the guitar.
Place the guitar on a sturdy work surface with an old towel or blanket underneath to prevent damage to the guitar's finish.
Insert one of the sleeve nuts in the tuning post hole to test the diameter of the old tuner hole. If the diameter is less than .382 inches, the holes will need to be widened with a drill to accept the Sperzel tuners.
Place masking tape over the front and back of each tuner post hole to prevent chip out if the holes need to be widened.
Chuck a 25/64-inch bit in the drill and centre the drill over each of the original post holes and slowly drill out each hole.
Remove the making tape from the headstock.
Place the guitar face down so that the back of the headstock is facing up, and use the installation template that comes with the tuner set to drill the set-pin holes. The instructions for using the template are printed on the template itself, including the size of the drill bit to use (#36/2.7mm) and the depth of the hole to drill 5/32 inch. To ensure that you drill to the proper depth, measure 5/32 from the tip of the drill bit and place a strip of masking tape around the bit, and do not drill past the edge of the tape.
Insert the tuners in the holes, making sure that the set-pins are sitting in the holes you drilled for them. The tuners with the longer posts go closest to the fingerboard, the midsized posts in the middle and the shorter posts the furthest from the fingerboard.
Insert the sleeve nuts from underneath (the top side) and finger tighten.
Place the guitar face up on the work surface and use the adjustable wrench to tighten the sleeve nuts,