Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove red and blue leads from the selector switch
Attach crocodile clips to exposed terminals

Measurement:

Measure the resistance across the exposed terminals on the selector switch.
Resistance should be open circuit.
Hold selector switch in reset position (R).
Resistance should now be short circuit.