Can you reset a guitar truss rod? How do you know if your truss rods are too tight or loose?

Yes, the re-adjustment can be done. When tight, the action is too low – if it is loose, the action is too high. The action is too low. Be careful – just move and check the effect in small increments. If you have chosen a string gage, or better give it to the luthier – show him how hard you are to play.