I'm working an a bass that has some fret buzz up and down the neck. When I turn the truss rod clockwise, the bow in the neck straightens and the buzz gets worse. When I turn it counter clockwise, the bow increases but only to a point. After a while the relief doesn't increase, the tension against be turning the truss nut get's lighter, and the tuning doesn't go flat from the neck bowing. The strings are a 130,105,85,65,45 set of DR Nickle Lo-Riders tuned to a regular tuning. If I tune the bass up a whole step, the relief increases and the fret buzz is reduced. What's going on here? Shouldn't the string tension at a regular tuning be enough to bow the neck? Could there be something wrong with the truss rod or the neck?