I took the plunge and removed the neck to install a shim. I used a business card I picked up at GC.
When I removed the neck, I found some small wood chips in the pocket, which I removed. I then traced the shim with the neck, and used an exacto-knife to trace inside the line. The shim goes from the end of the neck to the last fret. I didn't glue it or anything; just placed it there and re-attached the neck. I didn't know how strong I should tighten the screws so I kinda put 'em back the way I felt them when I took them out.
Neck looks straight... it definitely plays better now and I was able to lower the action on the upper frets as I wanted.
Sounds good... with the now lower action I discovered two frets that were a bit higher. I marked them at the point of contact with the string using a Sharpie. Then I used some sort of artist tape my youngest son has to protect the fretboard, and I used a regular file to work them down a bit. The frets were the 17th on the G and the 18th on the E. Using a small steel ruler I filed down until the frets were level (no rocking motion) with the two adjacent frets. The buzz is gone.
Now, bassbenj posted that he had taken out the fretboard on one of his basses and discovered the truss rod mechanism used on these basses. I recall him mentioning that clockwise tightens the rod and pulls the neck "away from" the strings, whereas counter-clockwise loosens the rod and allows the neck to be further pulled by the strings thereby creating more relief.
The neck on mine looks pretty much flat on the C side, and it appears to have a bit (a tiny bit) of relief on the B side. I've loosened both rods about 1/8 of a turn three times. Small moves. I want to see how the neck slowly reacts to changes.. it's a big chunk of wood.
So far so good! Next step is to file/sand a new Graphtech nut to size to replace the one it's in there now.