The 3 w.p. bolts were tight when I removed them, I did look the pump over & saw no sign of fretting where it might have scooted. When I started on the car I assumed there would be a broken belt.....when I saw it was in one piece, I assumed I'd find an exploded idler/tensioner pulley....when they weren't broken, I was puzzled (I hadn't discovered that the car had been repaired before as yet). When I took the tensioner off and compared it to the new one, I found the piece broken off and the pulley was rotated to a different location than the new one.....this made me assume that I had found root cause. I didn't try to disect it to see why it was not in the same position as the new one.
Mike Sal