Every gutar needs to be "set-up" (recommended at least once a year). Even BRAND NEW guitars! Most guitars have truss rod - which needs to be adjusted at least once a year. A truss rod is a metal rod that runs through the neck of the guitar, keeping it straight and playable. Due to weather and humidity changes wood is always changing and moving. If a guitar is not properly maintained the wood can change and warp beyond repair! A truss rod adjustment SHOULD NOT be tried at home - the instrument can be damaged very easily. There are several other steps involved in a set - up (listed below).

SET-UP

Neck adjustment (truss rod)
Action adjustment (string height)
Saddle adjusted for optimum playability (acoustic)
Setting intonation (Electric Guitar / Bass)
Fretboard cleaning and conditioning
Fret polishing
Electronic inspection / cleaning (Electric / Bass)
Entire guitar cleaned & polished
New strings installed, stretched & tuned

When finished your guitar will look and play better than new