I just recently bought a JTV-69S on Ebay. It is a 2013 model. The action was a bit high and when I checked the neck it looked like there was too much relief (bow). So I figured I would tighten the truss rod a bit to straighten it out. Now I'm no luthier but I have a fair amount of experience setting up my own guitars, making some minor adjustment and such. So I figured I'd start with a 1/4 turn and see what the result was. Well, the result was that by the time I reached the end of the quarter turn there was virtually no resistance at all on the allen wrench. When I turn in the opposite direction I do get resistance, but it also seems like the bow may become more pronounced. But I haven't tried going too far in that direction.
I've tapped on the neck and I don't believe the truss rod is loose or broken, but this is the first time I've ever experienced sort of a backwards response. To be clear, when looking from the headstock toward the bridge I have assumed that a clockwise turn would tighten the truss rod and straighten the neck (reduce the bow), while a counterclockwise would loosen the rod and allow more bow. I don't want to damage the neck/truss rod, but I would like to straighten the neck more. Yet, if I continue to turn in the clockwise direction it feels like the rod is just freely turning and nothing will happen.
I realize the best advice will be to take it to a pro, and I may end up doing that, but this has me puzzled. If I'm doing something wrong I'd like to know. I'm assuming the thread is not reversed.
Anyway, thanks in advance for your input.