[Chalkie]

Sounds like the slipper plates are touching the spur, if the pads don't sit proud of the spur the edge of the plates sits on it instead, I know people have turned the plates down on a lathe so they can fit inside the pad recess and can't touch to avoid this. You mate may have slightly thicker pads or a spur with a shallower recess which is why he isn't having this problem.