Set Appliance State:
Set Multimeter to Resistance 
Isolate Mains Power to appliance as per TOPs P4
Measurement:
Disconnect both the spaded wires (Orange wire and Blue wire) from the Reset Switch.
Connect the multimeter across the Reset Switch spade terminals.
With the Reset Switch in the rest position an open circuit measurement should be observed, when depressed the Switch should provide a short circuit measurement.
Reconnect wires after test.
Connect the multimeter across the Reset Switch spade terminals.
With the Reset Switch in the rest position an open circuit measurement should be observed, when depressed the Switch should provide a short circuit measurement.
Reconnect wires after test.
Isolate as per TOPs P4
and refit as necessary