There are many different styles of electric guitar tuners or machine heads. Some tuners have notched string posts like classic Tele tuners and some have string holes like modern Strats.
Other tuners have locking mechanisms to clamp the strings in place while most tuners don't. There are many different styles and brands of tuners that essentially do the same thing: try to keep your guitar in tune. I have written about bunch of different problems with electric guitar tuners as well as various ways to fix and install electric guitar tuners. Please use the list below:
There are many different ways tuners can be broken. The two most common tuner problems are worn tuners gears and broken tuner buttons.
Many tuners wear down over time. The gears inside the tuning machine wear down from constant pressure and no longer fit together or grip each other properly. Worn gears can also cause tuners to skip gear teeth. You will most likely notice this, as you tune your guitar to pitch. A tell tail sign of severely warn tuner gears is the near inability to bring your guitar to pitch. As you place more tension on the strings, the tuner gears reach their maximum pressure and start to give. As you continue to turn the tuner buttons, the string doesn't increase tension because the tuner gears are stripped and probably skipping teeth under the pressure. There is no "fix" for warn gears. You just need to replace your tuners.
The second main problem that I see with tuners is broken tuning buttons. This is fairly common among acoustic guitars with alternative button materials like wood or celluloid. The tuning button can shrink with lack of humidity and crack. The button can also crack if the gears are not properly oiled. Stiff gears will require more pressure to turn the tuning post. Thus, you have a cracked or broken tuning button. Obviously, tuning buttons can also be broken by dropping your guitar and accidentally hitting it up against your amp.
There are two easy ways that you can maintain and take care of your tuners to ensure that they last the life of your guitar: keep you tuners tight and keep them lubed. Before you do any maintenance work on you tuners, make sure to remove the strings.
The first thing that I always check before I restring a guitar is whether the tuners are tight. There are three usual places to tighten a tuner.
The first screw anchors the tuner onto the back of the headstock. Some modern tuners don't have these screws, but the vast majority does. Although unlikely, these screws can come loose. This screw does not hold the tuner on the headstock. It merely anchors the tuner in place so the nut on the top of the headstock can tighten the tuner onto the headstock.
The second place to tighten the tuner is the nut on the top of the headstock. This nut tightens the tuner on the headstock. It is important that this nut is tightened because otherwise the tuner can be loose in the headstock and the pressure from the strings can damage the tuner. Simply, take a wrench and tighten this nut down. Be careful not to slip with the wrench and dent the face of your headstock.
The last screw that needs to be checked is the screw that holds the tuning button its pole or drive. This can be tightened with a simple screw driver. Always make sure that the tuning button is tightened onto the tuner. A loose tuning button can be stripped or worse can crack.
As I mentioned earlier in this article, inadequately oiled tuning machine gears can wear prematurely resulting in stripped and ruined tuners. If you notice your tuning buttons are becoming increasingly difficult to turn, you may have to oil your tuning gears. For general maintenance, you don't have to oil them everyday or anything, but I would suggest oiling them once ever six to eight months depending on your playing habits. The oil will ensure the gears turn smoothly and lock easier as well as prevent them from freezing in place. Most tuners could go the life time of the guitar without having any trouble, but there is no need to take any risks. Your guitar will probably stay in better tune afterwards anyway. Simply take some Big Bends Nut Sauce or generic, light sewing machine oil and drop a couple drops around the outside of the string pole. These drops will slowly drip down into the gears. As you oil is dripping into the gears, turn the tuning button to grease all the gears. That's all there is to it. Your tuners should be nice and smooth!
There are generally two parts to a guitar tuner that ever need to be replaced: the entire tuning machine and the tuning button.
Replacing a tuning machine button is quite simple. Take a small screw driver and unscrew the screw on the end of the tuning button. The tuning button will slide off of its post. Next, just buy the same style tuning button and screw it in place.
Replacing the entire tuner is a bit more difficult than just replacing the tuning button. Before you go ahead and buy a set of tuners, you should make sure that you are buying the right set.
Electric guitar tuners come in all different shapes and sizes. It can be over-whelming to try to pick a tuner at first. If you are replacing broken tuners, I would suggest buying a set of the exact tuners that were on the guitar to begin with. That way you know the tuners will fit. If the original tuners are no longer available or you want to upgrade the tuners, you will have to take a few measurements and decide on a couple key specifications.
There are a few measurements that you will have to keep in mind.
When buying a new set of tuners, you will have to decide on a gear ratio. A tuner gear ratio is the ratio of tuner button turns compared to the string post turns. For example, a 25:1 gear ratio tuner will turn the tuning post 1 time for every 25 times the tuning button is turned 360 degrees. The higher the gear ratio, the more minutely and precisely the strings can be tuned. You may have noticed when you tune your strings by ear, you have to tune your strings high and adjust them down to the proper pitch. This is largely due to a low ratio. Now you might think that you should get the highest ratio possible. That might not be the smartest idea. Extremely high ratio tuners can be a pain to string up because the tuning buttons have to be turned so many times. Also, just because a tuner has a high gear ratio does not mean that the tuner is of high quality. Some common tuning machine gear ratios are the following: 14:1, 15:1, 18:1, and 20:1. Tuner gear ratios are primarily based on preference. Some players prefer higher gear ratios while others can get by with lower ratios. The average guitarist can play with 14:1 ratio tuners.
Tuner brand names are like most other guitar parts--largely based on personal preference and customer loyalty. Most companies make a line of descent tuners and a cheap line of tuners. I don't know that I can tell you what tuners are the best tuners. I can only speak on experience and personal preference, but I like Schaller and Gotoh tuners. I also think that Grover makes some descent less expensive tuners.
Most guitars sold today have non-locking tuners or regular tuners. Some more expensive guitars like some PRS models have locking tuners. These tuners have a nut either on the top or bottom of the tuners that clamp down on the string to prevent it from slipping in the posthole. Regular tuners usually need the string wrapped around the string post about 3 times to prevent string slippage. Please see my article about restringing an electric guitar for more details. Locking tuners, on the other hand, lock the string in the posthole, so it cannot slip. Locking tuners make it easier and faster to restring your guitar because you don't have to wrap and unwrap the strings from the tuners. Locking tuners also weigh more than non-locking tuners. As far as actually keeping your guitar in tune, both work equally well. The difference between locking and non-locking tuners is larger based on preference. I have built guitars with both locking and non-locking tuners.
Many Fender guitars have bushing pressed in the holes in the headstock. These bushings are often called ferrules. The holes for the bushings are drilled undersize, so the bushings must be pressed in the holes tightly until the lip of the bushing is pressed flat against the top of the headstock. The bushings act as a guide for the tuner posts and allow them to fit snuggly in the headstock. These bushings are tightly pressed into the front of the headstock with a spindle of a drill press, hydraulic press, or clamp.
Because the headstock holes are slightly smaller than the bushings, you must be careful when pressing the bushings in or out because you can easily crack the finish on the headstock. If you don't have a drill press or hydraulic press, you can use a C-clamp to press the bushings in and out. To install a tuner bushing, prepare the holes and place a bushing squarely in its hole. Take a C-clamp and carefully place the top of the clamp on the underside of the headstock. Slowly tighten the C-clamp until the bushing lip is flush with the top of the headstock. To remove a tuner bushing, you will need a dowel that is the same size as the outside of the bushing. You will also need to cut a block of wood slightly wider and taller than the bushing. Now drill a hole that is larger than the bushing through the wood block. Next, place the dowel on the bottom of the headstock and the wood block on the top of the headstock with hole in the block is completely around the bushing. Now take a C-clamp and slowly tighten the dowel squarely onto the bushing. The bushing will press out of its hole and fall into the wood block. Be careful not to crack or dent the finish on the headstock with the C-clamp.