It sounds as if you have a leak in the system and it is not causing the Sequence Pressure Switch to toggle between lock and unlock. This switch has to make in order to switch power/direction of the motor. This switch is connected to the blue and yellow wires, on one side, and the motor for the pump on the other. A diaphragm actuator drives it back and forth. When you bench tested, did you connect to the pump itself or use the blue & yellow input wires?

Also, I haven't had to deal with any problems in the door switch so haven't seen the disentegrating problem. According to the diagram, connections for that switch are yellow=switch #2 and blue= switch #3.

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Sam

84 300SD 350K+ miles ( Blue Belle )