Recently bought a LTD vintage 214 Fretless. It did not come with a truss rod wrench. I have a full set of ball end Allen wrenches (or hex keys) Metric and SAE and none of them work. The short end of the wrenches aren't long enough to reach the nut, and the long end of the wrench doesn't follow the contour of the pocket where the truss rod nut is, and can't make contact with the nut. Does anyone know what size wrench is needed and where I can find one? Thanks.