After three years the strings on my Vintage Blonde seem to be higher than when I first bought it, so I decided to try tightening the truss rod. After about a quarter turn clockwise the neck doesn't seem to have straightened any and the strings haven't come closer to the fretboard. My question then is : How much of a turn does it usually take to bring the strings lower ? Will I have to give it half a turn , or perhaps even a full turn (meaning 360 degrees)? Obviously I am afraid of damaging it. I'd appreciate any insight , friends !!!