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I've got an old Martin guitar that I want to get back into playable shape. The strings are really high on the high frets (8th fret and above) but are fine at the lower frets. The neck is pretty straight, but it looks like the bridge is pulling away from the body causing high strings in the upper fret range. The top of the guitar just before the bridge looks like it is warped which may be causing the uneven bridge.

I don't think I have the tools or ability to repair this myself. Would it be worth it to get it repaired? Any idea how much it might cost? I've considered buying a new guitar, but this one holds a lot of sentimental value that I would love to get it playable again.

Thanks for your help and suggestions.

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    First thing is to take off the strings (or release the tension) and leave for a few days. See if the levels change. – Tim Mar 31 at 18:30
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I'll say what I would do and let you decide for yourself if my hunch is valid. Before taking the strings off or reducing the tension on the top, I would use a small mirror mounted on an extending rod similar to a dentists mirror for examining teeth in the back of your mouth. I would use the mirror inserted into the sound hole to inspect the internal braces inside the guitar. the string tension should be maintained because releasing that tension would probably allow to top to move back into place and make it more difficult to notice any broken glue joints or cracked braces. If you find the problem then you can decide whether to repair it yourself (if you're good at this sort of thing, and have the tools you'll need), or find a qualified repair person to fix the problem. The guitar probably is valuable enough to warrant repair, but a good luthier can tell you for sure.

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Based on what appears in the photo, it's a bit hard to detect - you should take it to a luthier (guitar repair specialist) and have someone skilled repair it. I would not suggest trying anything yourself. By having a luthier repair it, you are able to look at years of a playable, great instrument. Martin is great brand of guitar. Take it to a few different places and they will give you estimates. A Martin is usually worth repairing, in taking it to a few places, if you find a good luthier they would tell you if it's not worth the repair. You can also look at current new Martins to understand the cost of a new one.

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This is a fairly common issue on older acoustic guitars, especially those that were built for lower tension strings and have been strung with modern, high tension strings. Or those that were built with marginal bracing and top thickness to begin with, even for their original strings.

It's hard to dictate a repair without having the instrument in hand. This can be as simple as switching to light(er) strings, or as complex as major structural modifications which may require hours of skilled labor.

In terms of steps you can take yourself, taking off the strings and leaving it for several days (or a week) can be a good start - if the bridge returns to level, you can re-string with lighter strings, adjust the truss rod if needed to get the relief correct (based on the string gauge change - you do not want to try to compensate for the bridge issue with the truss rod), and hope for the best.

If the guitar has changed environments recently, consider the impact humidity may have. Guitars that have lived in a humid environment but were recently brought to a less humid environment will often suffer from a sunk bridge like this, due to changes in the geometry of the bracing as the wood shrinks due to lower humidity. If you know that the humidity has changed recently, you can consider taking the strings off, storing the guitar in a case with a guitar humidifier (basically, a little device intended to slowly release humidity inside an instrument case), and check after a week or two - then restring the guitar and keep it stored with a humidifier for the future.

Other than that, you are best off taking it to a qualified repair tech who has experience with acoustic guitars in order to get their evaluation on the instrument. Sometimes these problems can be caused by structural failures within the instrument (the bridge itself, or bracing inside the guitar, may become unglued over time). Those issues are sometimes awkward to fix but usually not expensive (figure an hour or two of labor if you're lucky). In other cases, if the instrument was underbuilt to begin with, techs can install a "bridge doctor" or other reinforcement designed specifically to address a sunken bridge. The most severe cases will sometimes require a neck reset or changes to the internal bracing. The good news is, these reinforcements are usually effective and permanent. The bad news is, they can be expensive (hundreds of dollars and up) and they will usually impact the tone of the instrument.

Whether or not a given instrument is "worth it" to repair is really up to you, especially in the case of an instrument with sentimental value. Most repair techs would probably advise that it's not worth it to reset a neck or do major structural repairs on an average or lower cost instrument, but many Martins are in the price range that would make at least basic repairs worthwhile.

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  • When you say "older, built for lower-tension strings, you must be talking 80+ years or something". String sets with .012 and .013 high E have been available and strung on guitars for decades. – Kaz Apr 1 at 2:15
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    @Kaz - given that it's a Martin, it could be 200+ yrs old... – Tim Apr 1 at 7:50
  • Yes - given the long history of flat top acoustic guitars (and Martin's part in that), you never know - I guess I just assume that "older" usually means "from the era when gut strings were still common." But at any rate, even among modern flat top steel string folk guitars, typical gauges tended to drift over the last half a century even, and major manufacturers adjusted their designs to account for that. The difference in tension between a .09 and a .014 can be twofold. I don't think many people realize that even among "typical" gauges there is such a huge difference. – dwizum Apr 1 at 10:49
  • Keep in mind that Martin basically invented x bracing as a way to deal with increased tension from "new" (at the time) string preferences in the 1800's - the entire history of flat top acoustic guitars has basically been an evolution aimed at making them louder, which has usually meant finding ways to support louder, higher tension strings. Of course, we may be venturing way too far down the rabbit hole for the guitar in question! – dwizum Apr 1 at 11:13
  • The tension difference between .009 and .014 is more than twofold, if they are made of the same material and tuned to the same pitch, at the same length (i.e. "all else being equal"). The cross-sectional area of a .014 is 2.4 times greater. – Kaz Apr 1 at 16:46

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