Well, I wasn't there. So, at the end of the day, I wouldn't pass judgement on those that were. But I've seen 50s shoot with large amounts of grit, sand etc in them. Once that baby gets going it's got inertia on its side.
From my own experience, like I said earlier, these MOS involved here don't know or look after their weapons the same way an infantry soldier would. It seems incomprehensible to me that three different weapons systems failing would be the reason this convoy met the fate it did. I suppose it could happen and I won't rule that out, but I don't see how one could rule out operator level maintenance either.