One of the most important aspects of purchasing a guitar is the condition of the neck. The state of the neck determines the degree of comfort ( or discomfort ) for your fretting hand. A bad neck may result in a guitar that is difficult to play, or even unplayable.

Things to look for:

Straightness:
If you do a search for any type of guitar on Ebay, you'll find many descriptions include statements such as "neck is straight as an arrow". You may want to ask the seller for a bit more clarification. In reality, a guitar neck should have a slight bit of "relief", or lengthwise curvature, in order for the strings to vibrate without buzzing. This curvature generally causes a slight dip in the middle area of the fretboard, with the ends of the board closer to the strings. Such a shape allows for the string's vibration, which creates an elongated elliptical path. The amount of relief in the neck is adjusted with a truss rod. Straightness of a neck can be checked by turning the guitar so that the neck's edge is facing up, then sighting along the fretboard's edge. ( Note: an experienced repairman will be able to see problems here, better than a beginner can ).

• Warping: Sometimes the wood of a neck will bend in an undesirable way along the length of the fretboard, causing unwanted dips or valleys that affect the guitar's playability. Adjusting the truss rod may fix a minor warp, but curing a bad warp can be an expensive repair job. Always ask a seller before you purchase a guitar, if there are any structural problems with the neck.

• Twisting: A twist can be even worse than a warp. When a neck is twisted, it is warped across the fretboard ( sideways ). Bad twists will not respond to truss rod adjustments. They can be more expensive to fix than warps, or they may be so bad as to render the guitar unplayable. Again, ask first about warps and twists before purchasing.

Action:
The action is the distance of the string to the fretboard. Many guitar players who play rock music, favor low string action as it is easier on the fretting hand and enables the musician to play faster with less effort. Action is a very personal choice, closely related to the style of music that one plays. A bluegrass player needs a higher action for better, crisper definition of notes, and a blues player may prefer higher action to let the notes "sing" better. A player's picking technique will directly affect how low the action can go: if you bend a lot of notes and / or hit the strings really hard, your action must be set a bit higher to avoid string buzz. The downside of low action may be some loss of tone and sustain.

Truss rod:
Most guitars except for classical nylon-string guitars have a metal rod embedded in the neck. A player can adjust the rod, which will in turn adjust the amount of relief in the neck. Tightening the rod brings the fretboard closer to the strings, loosening it creates higher action. In many cases, a very slight adjustment will make a big difference - moving it an 1/8 of a turn or so, can do a lot. The truss rod's pressure works against the tension on the neck exerted by the strings, creating a yin-yang interplay of striving for a perfect balance. Changes to one will affect the other: moving the rod will change the action - as will detuning strings, or going to a different string gauge. It is imperative to have a well-functioning truss rod if you want to have a playable guitar. If considering the purchase of a guitar on Ebay, ask whether the truss rod is fully adjustable - on some guitars, a rod can become frozen or stuck, in which case you won't be able to adjust the rod to get the neck to your optimum preference. WARNING: Be very careful when tightening the truss rod - if you break it, you'll have a very expensive repair job. Actually, you'd probably crack the fretboard or separate it from the neck, before the truss rod breaks - metal is stronger than wood. You could also strip the rod's nut or threads. In any case, the result will be something that is no longer a functioning guitar. If you have any doubt about your abilities to adjust a truss rod, take your guitar to a qualified repairman. And please do not try your very first truss rod adjustment on a treasured or valuable instrument - you may end up with an expensive repair job for your trouble.

Bridge Saddles:
After initial adjustments to the truss rod, a player can fine-tune their action by tweaking the bridge saddles on their guitar - assuming these are adjustable. On acoustic and classical guitars, they aren't. But on electric guitars and basses, you can lower or raise the bridge to optimize the action to perfectly suit your tastes. If you like low action, here's a useful technique: lower the bridge to the point where the strings really buzz, then begin raising the bridge until you reach a point where the buzzing stops. You now should have low action without the buzz.

Frets:
Along with string action, the type of frets you prefer is a very personal choice dictated by the type of music you play. Rock and blues players generally like wide and medium-to-high frets that allow for easy string bending. Ask the seller about the height and width of the frets before purchasing an instrument. Also ask about their condition - worn frets may cause buzzing in certain parts of the fretboard. The obvious signs of a worn fret are grooves in the fret from the strings, but frets can also be flattened by lots of string-bending. Worn frets can be corrected with a fret leveling by a skilled guitar repairman. However, if a majority of frets are uneven and/or severely worn, the only remedy is a complete fret replacement, which is generally quite expensive.

Strings:
The final part of the equation is a very personal choice - the kind of strings you prefer. Heavier strings will usually exert more pressure upon a guitar neck, and may take a bit more effort on your part to play. Some players like heavier strings because of increased sustain and quality of tone. Other players enjoy the ease of playing associated with lighter-gauge strings. Just remember the point above regarding the truss rod / string tension balance - if you change to a different string gauge, you probably also will need to tweak the rod.

Climate Changes:
One of the major factors in wreaking havoc on guitar necks is seasonal climate change. As summer approaches, fretboard woods typically swell from the increased atmospheric humidity. This usually brings the fretboard closer to the strings, sometimes causing buzzing. With the arrival of winter, the dry air pumped from our furnaces causes a loss of moisture in fretboards. Usually, this will result in the fretboard contracting and pulling away from the strings, causing an increase in string height and thus a stiffer action. In general, loosening the truss rod in summer as the fingerboard swells and expands, will keep the buzzing at bay. Likewise, tightening the rod in winter as fretboard loses moisture and contracts, will usually be enough to maintain a comfortable action. Note that these are general guidelines; if you live in a climate with marked seasonal changes, you should always monitor your neck year-round to see how the seasons affect your neck. And as always, be careful when turning the truss rod, so as not to over-tighten. Here's a simple and no-cost way to help maintain your guitar: store it away from heating / air-conditioning vents, and away from windows or outside walls where temperature differences will wreak havoc with the wood.

Wrap-Up:
If these concepts are new to you, this information could possibly be discouraging. It may seem that this is an awful lot of work to do, to maintain your guitar's playability. It can be a real bummer to pick up a prized instrument that somehow does not "feel" right, when only a few weeks ago, it felt perfect. You have several choices:

1. Give up on guitar entirely. ( No, don't do that ! ) It's really not as bad as it appears initially. Some other options are available to you:
2. Find a reputable luthier / guitar repair technician, and if you live in a variable climate, take your guitar in for a routine setup at least twice a year. It's usually not a very expensive procedure, and you'll be guaranteed to have an instrument that plays optimally year-round. Be sure to discuss your action preferences with the technician beforehand, and ask him to give your instrument the "once-over" before you leave it with him; he may be able to spot problems and recommend solutions for you. Some technicians are very generous in sharing their knowledge, so you can ask questions about how to set up your guitar. Before you know it, you may well be on your way to learning how to do it yourself !
3. If you want to learn to do it yourself, learn from a pro: go to a luthier-supply vendor ( do a Web search for "guitar repair supplies". There are a number of books and videos on setting up guitars that can be very useful learning tools.
4. IMPORTANT ! If you want to learn to do it yourself, practice on a "beater" instrument until you are confident in what you're doing. Stay away from that treasured instrument of yours ( especially if it's "vintage" or collectible ), until you have the knowledge to work on something so valuable without destroying it.
5. If you still like playing guitar, but simply HATE everything about wood and its mercurial unpredictability, try a St___er, Mod___us, or other instrument with a composite neck. Such inert materials do not move the way that wood does, and are generally extremely stable regardless of the climate. A couple of caveats: such necks do not SOUND the way that wood does, because they're not wood. Some players also do not like the way that they feel. Also, such instruments are generally more expensive than comparable wood-neck models, so if this is the way you want to go, you might want to start saving...And if you opt for a St___er , try one out before you buy - some players really freak out when confronted with a neck that doesn't have a headstock.

Guitars on Ebay:
You can find some remarkable instruments on Ebay and you can find some real lemons. To increase the chance that you'll choose a winner, here are some tips:

• Check their feedback rating. If there are negatives, read some of the negative feedbacks, and also read how the seller responds to negatives. You'll get a better idea as to what kind of person the seller is, and how they might respond to you in case of a problem. Also check the feedback-giver's feedback ratings; you may find that not all of the negatives were justified.
• Read the description carefully. If it is vague or if you have questions, ask them BEFORE you place a bid. Be thorough in your questions; ask about every possible aspect that is important to you. Definitely ask about the state of the neck. ( a sample query is included below ). If the seller does not respond to your query, or sends you vague or evasive answers, such a response should raise a red flag.
• Look carefully at the included photos. If they're blurry or otherwise inadequate, ask the seller for close-up photos. If no photos are included, and/or the seller refuses to send you some, then buyer beware !
• Obviously, a major disadvantage of buying a guitar online from someone you don't know, is that you can't try it beforehand. See if the seller offers a trial-run period in which you can give the guitar a good workout, and return it if not satisfactory. This can range from a simple "full refund if returned in __days", to a more complicated arrangement such as escrow. If the seller offers escrow as an option, agree to this ONLY if they use Escrow.com, which is affiliated with Ebay. Any other online escrow service should be suspect. There are a lot of Internet scammers out there who are eager to part you from your money.
• If the seller accepts PayPal, check whether you're covered under the PayPal buyer protection policy.
• Be sure to ask them about how they intend to pack the instrument - guitars can easily be damaged in transit if poorly packed. You're much safer if it ships in a hard-shell case, and if insurance is included. At the very least, it should be double-boxed and filled with good packing material. Also, the neck will suffer less stress if strings are detuned prior to shipping ( tuning down 1/2 to a full-step is fine ). Note: if the guitar will be detuned for shipping, the truss rod should also be loosened slightly.
• Be aware that the neck may need some time to "settle" once you receive it, especially if it needs to acclimate itself to a different climate. It may need an adjustment, or it might not. So, don't fire off a scathing negative until you've given the neck at least a week to settle down.
• Also, be aware that action settings are extremely subjective. Your seller's concept of "low" action may be far different than what you prefer. You may need to adjust it, or take it to someone who can do this for you.

Here is a sample query that covers the areas that I consider the most important. You're welcome to use it.

"hello, I have a few quick questions about your guitar on Ebay:

1. Any problems with the neck - any twisting or warping, or other structural issues ? Any prior or existing damage to neck ? Truss rod working properly ? How is the fret wear ? Any cracks at heel joint or around neck / headstock ?
2. Electronics / controls working properly ? Any excessive hum, hiss, or other non-musical noise ?

Thanks."

I hope you've found this guide useful. If you have any questions, feel free to e-mail me. I will occasionally update / revise this guide, so please check back once in awhile.