Re: Vintage Acoustic - Truss rod adjustment??
is it valuable? If so, take it to a luthier.
if not so much and you don't care all that much, there's a couple of options.
1) Chances are it's a single-action truss rod. See if you can adjust the nut. If it moves easily and is still on the truss rod threads, turning the nut clockwise = straighten out the neck. Counter clockwise = introduce more bow into the neck. If you get to the maximum adjustment range of the nut and the neck isn't straight enough, give it a couple of days to settle. If it still isn't up to par, go to #2 below, but before you do, loosen the nut.
2) See if you can find a straight beam. Clamp the neck to the beam. Not super tight, but gradually, every day, tighten the clamps a little bit more, until the neck is pretty much straight again. Could take several days. After it's straight, then tighten the truss rod nut until it's sitting comfortably.
Sometimes a neck can get so much bow on it, it puts an enormous stress on the truss rod and even tiny adjustments can be really difficult to do. By clamping the neck to the beam, you gradually straighten out the neck while relieving stress on the truss rod, all while making zero adjustments to the truss rod. Then when the neck is straight, adjusting the truss rod nut should be a breeze (provided the nut isn't rusted and stuck on the threads), and then the truss rod should be in its normal range of tension and adjustment, and can then do its job again.
3) I hope it's not twisted. If it is, you'll likely need to take it to a luthier. A twist can be worked out (depending on how bad it is) with careful clamping, but it's not always a sure thing.
