1. Loose Volume / Tone Knob

When the nut that holds a potentiometer (pot) in place is tight enough to hold it still, turning the knob simply rotates the pot’s shaft, giving you that volume or tone change. Here’s something I’ve heard a number of times: “well, my knob was just loose at first but now my guitar doesn’t even work!” So, what happens when it feels loose? The problem is that when you turn a knob that is not securely fastened to the body, chances are you’re turning the whole pot inside the guitar. Doing this will also rotate all the wires connected to the pot, potentially ripping them off or causing them to short somewhere.
So if you don’t want to rip wires off, (which you shouldn’t), the answer would of course be to tighten the bolt that holds the pot in place. Herein lies the next problem: once the bolt is tight enough to grip the pot (but not quite tight enough to hold it in place), just turning the bolt can also turn the whole potentiometer. The trick is to make sure you hold the pot’s shaft still while turning the bolt. I like to use a flat-head screw-driver in the slot to keep it still while tightening.

2. Loose Output Jack

There’s a couple different ways your output jack can be loose. One: your cable just seems to fall out, and two: the whole jack wiggles around. In the first case, more often than not you can fix this by adjusting the jack’s contact on the inside.
Take the jack assembly off, and plug your cable in. You can see where the cable’s connector makes contact – that long curved metal thingy. This is the piece that holds the cable in, so by removing your cable and gently pushing this piece inward, you should be able to create a better “lock” for your cable.
If your problem is that the whole output jack is loose, you have a similar problem to what I mentioned about the loose volume / tone knobs. You don’t want to just turn the bolt, you need to be able to hold the whole jack still while turning or risk ripping off more wires. The best way to do this would be to take the jack out, and literally hold it with your hand while tightening the bolt.

3. Loose Strap Buttons

It’s not uncommon for a strap button to spin in its place. While this might not seem like a big deal, if you aren’t using strap locks this makes it easier for your strap to slip off. Also, enough movement can gradually wear the hole that the button’s screw is set into, and eventually just not be secure anymore.
Typically, the cause for a loose strap button is that the screw just isn’t biting into enough wood. The simplest solution to this is to, well, add some wood. Toothpicks are great for this – simply remove the strap button, break up a couple toothpicks and put them in the screw-hole. You’ll notice a much more snug fit immediately.

4. Sympathetic Buzzing Sounds

Ahh the dreaded buzz. Most often, an annoying buzz is caused by a poor set-up or messed up frets. Occasionally, a different sort of buzz can appear from an entirely different source. These are tricky to pinpoint, but keeping with the theme of fixing loose components, sometimes you can erase these pesky sounds by tightening everything!
When you pluck a string, more than just that string vibrates. Everything on the guitar vibrates, so if there’s a particular component that’s loose, there’s a chance it will rattle. Confirm that every screw and bolt on the guitar is snug, from the machine heads to the saddles, and you may just save yourself a repair bill just by turning some screws!

5. Grime-encrusted Fretboard

Okay, so here’s the odd one out. No need to tighten anything here! Cleaning your fretboard may seem obvious, but doing it effectively isn’t always carried out. One of the big problems with keeping dirt on your fretboard (among others) is that things can build up underneath your frets, and eventually end up raising them. The last thing you want to do is bring your guitar for a fret level because too much dirt built up underneath the frets.
To really clean out your fretboard, I recommend spraying the board with a few spritzes of a bio-degradable cleaning solution (such as Simple Green), and then scrubbing with a toothbrush. Get in nice and close to the frets with the brush to try and remove any build-up that may already be present. As soon as you’re done scrubbing, wipe off the solution, and apply your lemon oil. You don’t need to do this every time you change strings, it really depends how much you play and.. how dirty your hands are. Which leads me to another point: wash your hands before you play! Your future self (and your guitar) will thank you.

Guitar Care 101 from MyRareGuitars.com

1. Kitchen Magnet Bar

While this is of course great for holding your knives and other kitchen tools, many of the tools you will be using on your guitar are made of metal and can be kept organized by putting one of these on your wall. Having metal tools strewn about your work bench is a recipe for making scratches and dents on your instrument, and it’s simply easier to find what you’re looking for when they’re hanging right in front of you. If you plan on doing work for others, keeping a tidy work space is a major selling point for your customers. If I went to drop my guitar off with someone and saw a work desk covered in tools, glue and sawdust, I’d be headed out the door! As a sidenote: make sure the bar is installed a safe distance away from where you’re doing the work. That is, not directly above the guitar… falling tools are even worse than ones on the workbench!

2. Tape

You can use different types of tape for many different things when it comes to guitar work. The best use would of course be for protecting the guitar when you are doing other work to it. We’ve all seen the green tape on the fretboard for when you’re doing fretwork – but that’s not the only use! Electrical tape is a must if you plan on doing any soldering. If you have any bare wires, or want to tie wires together to keep things neat on the inside, a small piece of this is the best way to go. You can use the same green tape you would for fretwork for other protective purposes, too, like if you have to do any sort of drilling into the body (bigsby installations, strap button installations, etc). On top of potential damage from hard tools, glue spillage is something that can cause you more grief in the future, and is best prevented by protecting the area you are gluing with some tape. For example, if you’re gluing in a nut or filling nut slots, lay a couple strips of tape on either side to collect spillage.
Another use would be a quick-fix for loose knobs. If a knob isn’t quite grasping the pot-tabs well enough, you can wrap a small piece of tape around the tab to “increase” it’s size, and allow for a more snug fit.

3. Black Sharpie

It may not be a professional re-touching job, but you wouldn’t believe how often a black magic marker can be used to cover up blemishes. If you’ve got a dark colored guitar with a small paint chip, some black binding with a ding in it, or a dark fingerboard with an imperfection, a simple dab with a black sharpie can virtually make the problem disappear in many cases.
In addition, if not for covering up damage, a marker comes in handy for when it comes time to level and dress frets. Drawing a line down each fret will give you a good reference point of which frets are actually “getting hit” when doing your fret level, and will also be a good indicator of the “crown” on your fret after you start using a crowning file. You can check out an article for more on that here.

4. Pencil / Nut Sauce

If you find that your guitar is falling out of tune easy, or strings keep “catching” when you tune them, it could be that you need to add a little lubrication to the nut slots. An age-old trick would be filling in the nut slots with a bit of graphite, most easily accomplished by drawing into them with a pencil. It seems silly, but it works! There are also products that exist that work in the same way. such as “Big Bends Nut Sauce”, which works just as well, if not better than the graphite.

5. Glue

OK, so typically you shouldn’t need glue for your average guitar set-up, and it’s sort of the last thing you want to use when it comes to “minor” repairs – but sometimes it’s necessary. Two types of glue would suffice for general work: a white wood glue, and a super glue. Sometimes frets can lift a bit from use (especially at their ends), and buildup getting underneath them. Before jumping to filing and fret leveling, you’ll want to make sure they are seated properly. An application of super glue with some downward pressure (clamps would be best if you have them) would help seat them, and keep them in place for when it comes time to take the file to it. Another common piece to come loose is the nut. Some would argue that if the nut on your guitar is loose, to just leave it – but I prefer to have it at least secure enough that it will stay on its own without string tension. Not so much glue that you need to saw it out in the future, just a dab; enough that a gentle tap while knock it out. While we’re on the topic of using glue for the nut, it will also come in handy should you find the need to fill in your nut slots. If a string sits too low and causes fret buzz, the simple solution is to use a concoction of super glue and baking soda to fill in the slot, and re-file so the string sits at a good height. An alternative to baking soda would be some tiny shavings of the nut material your nut is made of.

6. Razor Blade

This can be your fingerboard “deep cleansing” tool. You can lemon oil your guitar neck as much as you want – the fact is, sometimes dirt and grime gets stuck in the wood fibers and right close to the frets. In order to get it out, you’d need to get rid of some of the wood that’s holding it in. Here you would use the razor blade as a scraper – stand it up so it’s 90 degrees to the fingerboard, and scrape along the wood-grain (from fret to fret.) You can use sand paper to do the same thing, I just prefer to scrape, and easily get close to each fret with the blade. When finished, some steel wool will help polish up the board, and you can then apply your lemon oil.

7. Sandpaper

As mentioned before, this can be used for cleaning tough spots on the fingerboard like the razor blade. More often, however, sandpaper will be your best friend for everything that involves fretwork. Leveling? Sandpaper stuck to leveling-beam or straight edge. Polishing? Different grits of sand paper, starting from a low grit and working your way to a higher one.
Aside from this, sandpaper makes for a good shimming material if you need it. Save a few strips of your used sandpaper – that way, if you come across a bolt-on neck that needs to be raised at the heel, you can use however much sandpaper you need to act as a shim for the neck.

8. Toothpicks

Whenever you have a loose screw, toothpicks can help tighten their bite. Simply remove the screw, and put the toothpick (or part of it) in its hole. Tighten up the screw again, and the toothpick will act as a wood filler, making the screw bite securely into the guitar again.

9. Flat Shoelace

This is a great leverage tool. Sometimes volume and tone knobs are just on too tight to be lifted by hand, and many people would jump straight for a flat-head screwdriver to pry them off. This doesn’t always end so well – plastics can crack or break, and it’s easy to slip and potentially damage the guitar. A flat shoelace slipped underneath the knob will apply even force to its underside, and it’s a soft material so you can pretty much guarantee you won’t end up breaking the knob!

10. Water and Cloth

If you’ve got a guitar that is in desperate need of a wipe-down, before jumping to the WD-40 and chemical cleaners, first try a dry cloth, then a damp cloth. You don’t want to give your guitar a bath here, so be sure to dry any wet spots as you go. In many cases you’ll find this will be enough to get the cleaning job done, and you can add a little guitar polish to shine it back up. As an added note: even before you go at it with the cloth, you may want to blow or use some compressed air to get rid of any particles that may be on the guitar. Wiping the cloth around on it without doing this may drag leftover particles and leave behind nasty surface scratches.

Ten Cheap and Handy Tools for Guitar Work from MyRareGuitars.com