Basically, the neck can move because the holes drilled through the neck are just slightly larger than the neck screw shank diameter and there is usually a slight bit of clearance between the neck pocket and heel of the neck.
The procedure is pretty simple:
- loosen the strings a bit to reduce tension on the neck - keep enough tension to be sure strings are taught though.
- loosen the 4 neck screws, but not to the extent that the neck is real loose or floppy in the pocket......just loosen enough so the neck will have a chance to shift with a little bumping pressure (see next step below). Be sure to use a good screw driver of the proper tip size so you don't bugger up the screw heads. As mbe suggested, it might be good to loosen all the pickguard screws - I don't think its necessary to completely to remove them though.
- hold the guitar body firmly and give a gentle thump on the side of the neck near the nut with the palm of your hand to move it sideways. In your case you will want to bump it on the treble side to move the headstock toward the bass side. Shouldn't take too much neck movement to improve your string alignment down near the body. Just go easy at first.
- do this until the string alignment is where you want it and then tighten the neck screws, then the pickguard screws, and retune. Don't overtighten things! Good luck!
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