Baumatic BDW15 dishwasher lower arm not spinning HELP!?

Hello, The lower arm is not spinning, the top arm works very well, its not set to half load. The arm is clean and not jammed, no water is coming out of it or the pipe it fixes into.

I wonder if there is a fault in the switch (the box with two orange wires attached to the main pump) or if a signal is not being sent to the switch.

Does anybody know how I could test this. I am no electronics expert. I did think of using a battery to send a current to the switch and eliminate the the switch from the list of suspects but I dont even know what voltage to use.

I disconnected the switch last night and ran the machine, it not not appear to make any difference.

Any sugestions you have would be very much appreciated.