I have a JB2 bass that is having problems with the low E string. When I fret it at 7th position or above, all the way up fret board it sounds like it wants to create a harmonic with itself and consequently sounds like c--p on that string only. Have tried adjusting truss rod, string height and intonation to no avail. All other strings sound fine. Has anyone else encountered this, and have you been able to sort it out?