I got everything disassembled last week and one arm of the pressure plate is lower. It’s not obvious what the problem is as the set screws are all protruding above the lock nuts about the same amount. A picture is attached. I’m going to replace it with a proper diaphragm unit that should be used on the 4.2L motor. I measured the ring at the arm that is lower at 0.21” lower than the other two.
