Sega J Bass Neck and Fingerboard Leveling

I built a Sega J Bass a while ago and the neck has always seemed a little funky.  I had to have the action fairly high to avoid buzzes, but those buzzes occured only on the G and D strings and only around the 3-5th frets.  I finally took the time to diagnose the problem by straightening the neck via the truss rod.  I made a straight edge from a cheap aluminum yard stick and cut notches for the frets.  This straight edge showed that there was a hump in the fret board around the 3-5th frets under the G and D strings.  The frets were all in good shape so I carefully pulled them using a Stewart Mac fret nipper and set them aside for future use.  The fret slots were cut quite deeply by the manufacturer of this neck and small splines were placed in the outboard ends of the slots to form pockets for the fret tangs to sit in.  Because these pockets were deep, I didn't have to worry about recutting them in the areas that I planned on flattening.

I then set to work at leveling the hump.  I rocked a 24" long straight edge on the fret board and penciled an "X" over the highest spot.  I then used 120 grit paper on a small sanding block, knocked the area down slightly and repeated the process to remark the new high spot.  As the neck leveled, the high spot would move slightly until after about 20 or so cycles, the neck was perfectly flat.  I ended up having to remove material all the way up to the 13th fret under the D and G strings.

The fret board was checked to ensure that the 12" radius was unchanged and the frets were reinstalled.  Once in place, a fret leveler was used to hit the high spots and the frets were re-crowned, buff sanded and polished.  A fret rocker was used to find any remaining high frets and at last the bass was restrung and it now plays well with the action set at factory specs, something it was unable to do before.  A small bead of thin CA glue was wicked under the frets to make sure they stay in place.