I was able to "fix" the a few notes (lack of sustain) on the G string on a buddy's Fender Jazz by taking the neck off and installing brass inserts and machine screws in place of the stock neck screws. If anyone is looking to try this, It did require some drilling in the stock neck holes to make room for the inserts. after measuring, I used a drill bit stop so I wouldnt drill through the neck completely. Other than watching out for that, its a fairly easy mod, and holds the neck to the body very tight.