Most people are afraid to get anywhere near a guitar with tools. They're afraid of messing something up. They're right about some things, but wrong about others. There are a number of simple guitar repairs and adjustments you can do yourself. I've covered some of those below. As I said on the main page, however, if you have a very old or valuable guitar, don't fool around with it yourself. Take it to an expert. For that matter, if you're just uncomfortable with the idea of working on your guitar yourself, there's nothing wrong with having repairs done professionally.
These instructions apply mostly to acoustic guitars, although some are translatable to some electrics. Never try any repair without reading through all of the instructions first. Make sure you have all the tools and materials you'll need on hand before you begin.
If you're broke and adventurous, read on.
Fret buzz is what happens when one or more strings are too close to the frets. The only fret a string should actually touch is the one being played. If it touches any others as it vibrates, it makes an annoying buzzing sound. A little fret buzz is hard to avoid if you like low action. In fact, some people like a tiny bit of fret buzz. They say it adds "character." But a lot of fret buzz detracts from the quality of your guitar's sound. Fortunately, it's a very easy problem to solve.
The first step is to find out where the buzz is coming from. Mute all but one of the strings and play each fret on the unmuted string until you get a buzz. If the buzz begins at one of the top frets, the problem is probably at the nut. If the buzz doesn't start until you're closer to the soundhole, the problem is probably at the bridge saddle.
If the strings buzz at only one fret, that fret is probably out of alignment. I personally wouldn't want to try to fix a crooked or loose fret myself; I'd recommend taking your guitar to a repair shop to have it fixed. The repair involves pounding the fret into place with a rubber mallet, and for some strange reason, the idea of taking a mallet to my guitar makes my hair stand on end.
If only one string is buzzing, the fix is ridiculously simple. Take a bit of paper or aluminum foil and fold it up into a tiny square. Loosen the offending string, and stick the paper or foil between the string and either the bridge or the nut, depending on where the buzz started. Tune the string back up to pitch and try playing each fret on the string again. If you still get buzz, make a slightly thicker square of paper or foil and try again. Repeat the process until the buzz stops.
Yes, it's a kludge. It's a very nice kludge, and I've had the same bit of paper under my low "E" string for eleven years. Do not mock that which you do not understand.
If you're getting buzz from more than one string, you'll have to make a shim. A shim is usually a thin strip of wood veneer, but you can use anything that is thin enough and can be cut to the correct size. A shim is placed underneath the bridge saddle or the nut to raise it to the correct height.
If all the strings are buzzing, you need to put a shim under the full width of the nut or bridge saddle. If the buzz is coming from the strings on one side or the other, put a shim under only that side of the saddle or nut. If you're getting buzz from alternating strings, it's possible that your guitar's neck is slightly twisted, or some of your frets are coming up from the fretboard. A full-length shim may solve the problem, but you should probably take it to a shop to be looked at.
Now you can glue the nut or bridge saddle back in if you like. Some aren't glued on to begin with, and as long as the strings are holding them in place, there's no real need to glue them. If you leave them unglued, it will be easier to make more adjustments later, if you need to. If you do want to glue the parts back, use wood glue, and be sure to leave it plenty of time to dry.
Tuning machines are not expensive, and are quite easy to replace. If you have a broken tuning machine, it's probably best to replace it rather than trying to fix it. Sometimes a tuning machine just needs to be greased or unjammed, but usually when they stop working you should just put on a new one.
There are three kinds of tuning machines.
If your tuning machines are working smoothly, leave them alone. Don't try to do anything to a tuning machine without loosening the string it's attached to. The best time to clean and lubricate the machines is while you're changing your strings.
To lubricate and adjust tuning machines:
If one of your tuning machines is seriously jammed or broken, you'll have to replace it. If you don't have sealed tuners already, this might be a good time to buy a whole set and replace them all at once. A set of sealed tuning machines costs about US$50.00, and it's worth every penny.
Take one of your old tuning machines off and bring it with you to the guitar shop. The part of the tuner that goes through the headstock varies in diameter between varieties and brands of tuning machine. Be sure to buy a replacement that is the same size or larger. (If it's smaller, it won't fit snugly and the tension of the string will snap it.) If the new tuner is larger than the old one, you will also need to buy a reamer. (A tool for making small holes larger.) If the new tuners have screws in different places than the old tuners, buy some wood putty to fill in the old holes.
To replace tuning machines:
Sometimes the support braces on the inside of an acoustic guitar come loose. Usually you'll notice it when you start to hear an unexplained vibration in the guitar's body. Press down firmly on the top of the guitar while you pluck the low "E" string. When you press a spot and the vibration stops, that's where you have a loose brace. Now take all the strings off the guitar and reach inside. Find the loose brace and try to wiggle it. It may just be a little loose, or it may actually come off in your hand. If it comes off, don't panic. You can still fix it.
You will need wood glue and popsicle sticks. If the brace is still attached to the guitar, it will also help if you can find some kind of syringe with a tip wide enough to dispense glue and narrow enough to it in the crack between the brace and the body.