Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4

Measurement:

Check for continuity (zero resistance)
through the electrode assembly.
Check the gap between burner and rectification probe at the rear of the burner is 5-6mm.
Visually inspect the electrode and harness for any signs of moisture, ensure the electrode ceramic is not cracked or damaged and check that the harness is in good condition throughout.