Set Appliance State:
Mains Power Off
Gas Off
Set Multimeter to Resistance 
Disconnect connector marked M1/M7 from main PCB 23
Measurement:
Test 1:
With CH temperature selector set at maximum position measure the resistance across the violet wire (connection 2) and the pink wire (connection 1). The resistance measured should be approximately than 10 kOhms.
Turn temperature selector to minimum resistance should reduce to less than 100 Ohms
Test 2:
With CH temperature selector set at minimum position measure the resistance across the violet wire (connection 2) and the pink wire (connection 3). The resistance measured should be approx 10 kOhms.
Turn temperature selector to maximum position resistance should reduce to less than 100 Ohms.
Replace connector after test.
With CH temperature selector set at maximum position measure the resistance across the violet wire (connection 2) and the pink wire (connection 1). The resistance measured should be approximately than 10 kOhms.
Turn temperature selector to minimum resistance should reduce to less than 100 Ohms
Test 2:
With CH temperature selector set at minimum position measure the resistance across the violet wire (connection 2) and the pink wire (connection 3). The resistance measured should be approx 10 kOhms.
Turn temperature selector to maximum position resistance should reduce to less than 100 Ohms.
Replace connector after test.
Isolate as per TOPs P4
and refit as necessary