Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Remove the control knob from the CH Potentiometer on the User PCB.

Measurement:

Measure across the left and the middle terminals of the potentiometer that are located at the rear of the PCB, the resistance values obtained should be as follows:
Approximately 2K ohms with the potentiometer turned fully anticlockwise.
Approximately 0 ohms with the potentiometer turned fully clockwise.
Repeat this test using the right and middle terminals of the potentiometer, the resistance meter should read approximately 2K ohms with the potentiometer turned fully clockwise and approximately 0 ohms when it is turned fully anticlockwise.