I'm about to attack one of the ATE calipers on my wife's 740 to cure a squealing brake problem. I've been thinking it must have a stuck piston, but in doing a little pre-reading in Haynes (good illustration) and Chiltons (well....), they talk about the pistons being in the proper rotation and its effect on brake squeal. It seems there is a little step in the piston surface that meets the pad, and it is supposed be oriented to 20 degrees. I never noticed they were built that way. Does anyone know if it is very likely that they ever get rotated out of the proper position, and if so, what's the effect?