Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove X1 from the PCB

Measurement:

Test 1.
Measure for resistance across pins 5 (Brown) and 6 (Blue) of X1.
Expected resistance greater than 1MOhm (or O.L).
Test 2.
Measure for resistance across pin 5 (Brown) and Earth (Main terminal block).
Expected resistance greater than 1MOhm (or O.L).
Test 3.
Measure for resistance across pin 6 (Blue) and Earth (Main terminal block).
Expected resistance greater than 1MOhm (or O.L).