Fender US Vintage 57 Precision Bass Owners Manual - Page 7

If a string plays flat at the 12th fret when compared with the harmonic at that fret, turn the longitudinal screw counterclockwise so as to move the bridge bar toward the neck. If the note at the 12th fret is sharp when compared with the harmonic, turn the longitudinal screw clockwise so at to move the bridge bar away from the neck. These adjustments will be fractional and should be necessary only in rare cases such as when string gauges are changed. Check the harmonic and the 12th fret note several times while making the string length adjustment to be sure the bridge is not moved past the proper position. ADJUSTABLE NECK TRUSS ROD (See photo "B") A well-known feature of all Fender Bass Guitars is the adjustable neck truss rod which maintains perfect neck alignment. If for any reason the neck of your Fender Bass appears to require further adjustment, you can make the correction without the necessity of returning the instrument to your dealer or the manufacturer. ke1. ) PHOTO "B'