Took in a 1978? Yamaha FG375S on trade, for its age, great condition and the neck is so flat you could put a straight edge down it. Now my question, I've heard that with age the necks on these older acoustics can bow up from tension over the years. It's currently missing nut and saddle. The previous owner set it up with a chopstick for a nut and some folded business cards for a saddle, hey it worked surprise surprise. Once I replace the nut and saddle, should I store it with strings relaxed or leave it tuned?