Set Appliance State:
Gas Off
Set Multimeter to AC Volts 
Isolate Mains Power to appliance as per TOPs P4
Selector Switch in OFF position.
Remove Terminal Block Cover.
Selector Switch in OFF position.
Remove Terminal Block Cover.
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Is there Mains Voltage present across connections
(Brown wire) and (Blue wire) on the Terminal Block?
(Brown wire) and (Blue wire) on the Terminal Block?
Isolate as per TOPs P4
and refit as necessary