The other day a singer I work with gave me an old Martin Stinger bass he's had in his apartment for years and years. It needs a few bits and pieces like a jack plate, so I thought I'd have some fun with it: strip the body, drop in a set of inexpensive pickups etc..... The thing is, that there's an odd issue with the neck and truss rod. The neck is dead straight, measured with a straight edge: no relief, no back bow. If I turn the truss rod anti-clockwise, the neck stays still and the truss rod goes 'floppy' and loose: if I turn it clockwise it goes tight immediately and won't turn. I've set up a bunch of guitars in the past but not had this issue: can anyone help? I like the neck, so it would be a shame to waste it. Thanks!