Fix a Shifting Neck

Here's the method I used many times back in my repair days:

1) Drill the body holes so the screws slip through. Use the smallest diameter drill possible, that still allows the screws to slip through freely.

2) Line the entire bottom of the neck pocket with a piece of carefully trimmed wet/dry 320 grit sandpaper. Spray the back of the sandpaper with 3M spray mount adhesive, press into place. I like spray adhesive because the sandpaper can easily be removed with a heat gun or by soaking with naptha.

3) Using a piece of wound guitar string, drip a few drops of thin superglue into the holes of the neck. Spray with accelerator or allow to dry a few hours. This hardens the threads in the wood.

4) Rub wax (crayon will work) onto the screws threads. Mount the neck.

5) If you need to shim, use a 1/2" wide strip of window screen. With a paper punch, punch two holes in the screen where the two mounting screws pass through.

This method is rock solid. You won't be able to shift the neck unless you put your foot on the headstock! You could skip steps 3 and 4, but the superglue treatment does dramatically increase the life of the hole's threads.

The sandpaper and shims will have no detrimental effect whatsoever on the tone. In fact, the tone will be improved thanks to the increased stability of neck joint.

BTW, this is a great method for those 3-bolt 70's Fenders. Even with only 3 bolts it's solid, and you don't have to ruin the originality. Just be sure to replace that neck angle adjustment screw with a screen shim.