Q: I have a steel-string guitar, and sometimes I hear something rattling or vibrating. It’s not string buzz, and I don’t think it’s in the body. I think it’s in the neck or headstock. I checked all the tuners and their screws, but none were loose. Any suggestions?
A: It could be that the truss rod is loose, and is rattling in its slot in the neck. Even if the truss rod doesn’t need to be tightened to compensate for string tension, it should still be tightened down enough to prevent it from being loose. Depending on your guitar’s construction, access to the truss rod may be under a plate near the nut on the headstock or it may be at the body end of the neck, inside the soundhole.