robinc -
If the adjustments aren't holding very long, you've probably got bad fit of the threads to the insert. When your bass was born, it was a freshly cut brass insert that fit perfectly with an expensive stainless steel screw. The stainless steel is super hard and the brass is not, so over time, the fit can become loose, or perhaps somebody changed the screw.
The fix is cheap and easy. Go to your local hardware store and get a small tube of Loctite BLUE threadlocking compound. It's usually #242 when you get the tiny tube, but the same stuff might have a different number if you get a larger size. This is the low-strength/removable fomula. You unscrew the screw and put few drops of the liquid on the threads, then put the screw in where you want it. When the Loctite cures, in just minutes, it will fill the gaps between the threads and hold the screw in place enough that your probably should be solved.
If you change your mind, the compound will release with easy screwdriver torque - it holds just hard enough to keep things from untightening on their own, but is easily changed.
What you DON'T want is RED Loctite which will be sold right next to the blue stuff. This is a much stronger compound that effectively is permanent for small screws (you heat the bolt up to remove it, which would be bad news for your pickup adjustment screws!).
Somebody at Loctite must have a very strange sense of humor. They make three different compounds of varying strength, and identify them by the color, then put them ALL in red tubes! The third type of Loctite is green and is intentionally permanent.
Anyway, the application of about $0.10 of blue Loctite should solve your problem for good. This stuff is great and you'll immediately think of 20 annoyances that this will fix. You'll be tempted to put it in your gig bag, but don't do it! The same joker who thought that it made sense to color-code the compounds then put them all in the same color tube also designed a tube that will leak without fail at the slightest provocation. Unless you want everything in your gig back to have a bluish tint, just leave the little tube at home!
David Fung
