Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X20 from the PCB
Disconnect the inline connector to thermal fuse harness
(connector is situated behind air intake pipe)

Measurement:

Measure for resistance across each wire of the thermal fuse harness, pins 10 & 6 (brown leads) of connector X20 to thermal fuse connector.
Expected resistance continuity (zero resistance) on each wire.