Hello Hammurabi,

I don't know all the details of your particular situation but here are some real world "gotchas" that will definitely make it appear that you can't intonate your guitar or one string on your guitar. It may be that there is nothing at all wrong with your guitar.

One of the things that makes me doubt there is anything wrong with the truss rod on your guitar is that your other strings intonate without problem. Also you've indicated that you've changed the string to a brand new one. I am also presuming that you haven't had anyone do any work to the nut of your guitar. If so, that could certainly cause you intonation problems. I also assume from your conversation that this guitar was known to intonate properly at one time, before you started having problems.

Before trying to intonate your guitar, make sure your tuner has fresh batteries installed.

IF you are trying to intonate an acoustic guitar by using the mic of a guitar tuner, you need to pay attention to unwanted noises interfering with the tuner's ability to hear your guitar, i.e., fans running, close proximity to TV or Computer, dog barking, fluorescent lights, etc. Much electrical noise is polarized, that is, it is directional. Try facing in several different directions as you intonate to see if that makes any difference. Try intonating your guitar in another room, out in the garage, on the back deck, etc.

If you are trying to intonate an electric guitar, make sure you are plugged directly into the tuner and nothing else is connected, i.e., amps, pedals, etc. Perhaps there is something about the guitar cord you are using that is giving you problems. Perhaps it's the tuner itself. Maybe you should try a different tuner. All of the items in the above paragraph still apply (fans, lights, TV, computer, etc.). It's actually just as critical because the pickups on the guitar will do exactly what their name implies--"pickup" wanted as well as unwanted noises to keep you from intonating your guitar. Try different pickup combinations with the selector switch or switches.

Have a friend come over to your house with his guitar and tuner. See if his guitar intonates properly at your house with his tuner and cord. Then see if your guitar can be intonated with his tuner and cord. The opposite of that is to see if his guitar indicates correct intonation with your tuner and cord. Try going over to his house to see if the problem(s) follow you there or now all of a sudden, you can intonate your guitar properly. If that is the case, it indicates some kind of electrical noise is interfering with your guitar and or guitar tuner.

These are all common problems that guitar players overlook when trying to set-up their guitar. I hope this information helps.

Best wishes,

Bobby Howe