I am seeing the same type of problems. My blue tail block simply doesn't have any thread for three of the eight screws. I know that I haven't stripped them, because I could never get the screw to start "grabbing" the threads in the first place.

Two of the thread holes that don't work on my block are the short screw holes (the ones which accept screws that don't go through the other lower frame). If I simply don't put the cute blue screw washers on the screws in these holes, then the screws do deep enough to start threading. I am not sure if the screws are too short, or if the threads don't start till too deep.

One of the long screw holes (the one with the screw that also passes through the lower frame) is totally without threads. When I first assembled it, I put the screw in and it slid all the way in till the screw bezel was flush with the frame. Not good.

I will call Align on Monday and see what they say.