[TARNATION !!!]

One more possibility comes to mind - replacement screw. Dean is correct. When leaving the factory, the screws are in line with either the long axis or vertical axis, with the exception of a few that are at 45 degrees to the long axis and those are somewhat intuitive. These pics are from the Grades Tab on our site - not mine (I wish ! ) Any of the standard screws not in this alignment have been completely replaced with a problematic screw or they have been removed and not returned to correct location or correct final resting position if in correct location. At least that's my story and I'm sticking to it unless of course proven otherwise. Never say never. Never say always but... there is a high degree of probability this might be the case. Cheers, Jack