Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Disconnect the Main PCB Connector marked PL5 from the PCB

Measurement:

Measure the resistance between the two Grey wires on the CH Potentiometer.
With the Potentiometer turned down to position 1 a reading of approximately 5 K ohms should be obtained.
As the Potentiometer setting is increased the resistance should reduce.
A reading of approximately 1 ohm should be obtained once the Potentiometer is increased to its maximum setting of 8.
Replace connector after test.