Set Appliance State:
Gas Off
Set Multimeter to Resistance 
Isolate Mains Power to appliance as per TOPs P4
Measurement:
Disconnect the two Red wires that connect the transformer to the PCB noting their position. Measure the resistance across the two Red wires.
The resistance measured should be approximately 125 ohms.
Reconnect wires after test.
Note:
Transformer is situated inside the control box, the control box will have to be opened to provide access to the leads. Care should be taken when opening and reassembling control box.
The resistance measured should be approximately 125 ohms.
Reconnect wires after test.
Note:
Transformer is situated inside the control box, the control box will have to be opened to provide access to the leads. Care should be taken when opening and reassembling control box.
Isolate as per TOPs P4
and refit as necessary