I have an older SX 34" scale fretless neck that is making a crazy noise, but only at the first fret. Here's the issue: across all 4 strings, if I hold down the string at the first fret-line and pluck, I hear a terrible metallic rattle that resonates throughout the neck. The rattle sounds like it's coming from inside the neck right behind the first fret. If I move my fretting spot 1/2 step, there's no issue. I have tried this neck on several bodies and the problem follows the neck. I know it's a cheap neck, but I'm curious as to what other hardware is part of the truss-rod system that could possibly be loose/broken, etc. I can add/remove relief using the truss-rod, so the truss-rod is at least functional. The nut is solidly in place. I even put a spacer under the G-string (to bypass the nut temporarily) and the noise is still prominent on the first fret. I'd be interested to hear what someone here thinks could be causing this rattle. Thanks.