The neck on this Hofner Colorama was originally quite badly back bowed, as shown here: In an effort to rectify this, we’ve tried three different approaches, as follows: 1. While re-radiusing the fretboard, more pressure was applied towards the middle of the neck in order to remove more fretboard material in that area. This would not straighten the neck, per se, but it would reshape the top of the fretboard in such a way that its top would end up being flatter. 2. When refretting, the fret slots were widened. When frets are forced into narrower slots, this has a tendency to force the neck to back bow, so we wanted to avoid this at all costs. The slots are still narrow enough to grip the new frets, but are certainly not overly-tight. 3. Obviously the truss rod nut was slackened as much as possible. In fact, even with the nut removed, the neck still maintained a back-bowed shape. It was noticed that the washer under the nut was wedged into place, and it was suspected that it might be pre...