I recently got a used Jazz V off ebay and have been trying to set it up properly; I followed the extremely useful information on
this thread and others here, but couldn't get to where the action was right without fret buzz. I fiddled with the truss rod (which I hate to do), the saddle height, took a little off a buzzing fret, but nothing seemed to fix the problem. Finally, after reading the problems diagnosed
here , I checked and found that the neck had been shimmed.
So, to anyone else setting up a used bass, save yourself some trouble and make sure the neck hasn't been shimmed before performing all the setup steps.