Ahhrrgghh!!!

Nothing I do gets me any closer to getting this G string to play nice...

Filed the plastic nut which had nil noticeable effect.
Replaced the nut with a bone nut... a slight improvement... now the 2nd fret is only about 2 but closer to 3 cents off (high/sharp), and a Am or D or A chord still just sounds wrong, and worse if you add any gain in the amp. The open G and at the 12th fret is perfect. By the tuner all other strings/notes both open and fretted are 1 cent or better. 2nd fret bar looks, feels and measures fine. Play above the 5th fret is fine, and 3rd fret and above is often quite passable, It's just those finger chords that include any of the first 3 frets on the G string that sound off...

Hmmmm...