Looking at a fretless 74 jazz. Truss rod has been replaced, new ebony lined fingerboard has been installed. Has aftermarket basslines stack jazz pickups with preamp (coil tap, etc). Not sure if re-finished, but probably was at some point. The truss rod thing scares me a bit. I have no experience with those kinds of repairs and what effect they have over the long term. Too many fleas on the dog? I can't play it before I buy it, but will be able to return if problem. Have been told neck straight and true. Any thoughts?