You can get new adjustment screws at the dealer, NAPA might have them on hand, but not likely. You can also usually order them through
Engine Builder. You might as well as order enough to replace them all. Often the screw gets a worn spot in them which can cause the adjustment to reset itself to the worn spot overtime. It doesn't take a lot of force to tighten them up, the torque value is only 18ftlbs.
