Dip in otherwise flat 4001 neck

[antonius]

Hi there,

I would appreciate some advice. I have been adjusting the neck on my '75 4001 recently to try to get is just how I like it, i.e. flat with a low action. After a few days of gradually tightening the truss rods I have the neck fairly flat over most of its length but I don't seem to be able to eliminate a slight bow or dip from after the 1st fret to about the 4th fret, noticeable only on the E side of the neck. I have a generally lowish action (between 2/32" and 3/32" at 12th fret) and the bass plays and feels great further up the neck but just doesn't feel good when fretting the 2nd and 3rd fret on the E string - the action there should be lower than it is that far down the neck. By the way the nut grooves are filed low so that there is minimal clearance of the 1st fret - the problem starts after the 1st fret. I'm not sure that further truss rod adjustment is the answer because when I fret the 1st and last fret together to view the relief the string is already touching the frets from about the 7th fret upwards on the E string (but with a couple of business cards worth of relief at 3rd fret) so it might introduce a back-bow further up the neck before is sorts out the problem lower down. I recently changed to lighter lower tension strings (DR High Beam 40-60-80-100)and this helped flatten the neck generally but didn't cure this anomaly. Is there any way of eliminating a dip such as this without major surgery?