I have something wierd happening to somewhere around the 15th to the 20 fret on my bass where i get two tones, meaning the one note basically pulsates because the two frequencies of the pitches are so close. Its almost like a scofield tone, cool, but not all the time. Ive already intonated my bass, and the neck is fine. One friend told me that it needs fretwork, but before i do that i was wondering if youve heard of this before and if theres an easier fix. ~Thanks!