Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Gain access to burner
Disconnect inline connector to the rectification electrode

Measurement:

Inspect the rectification electrode for any signs of
damage, cracks to the ceramic or build-up of debris.
Check the distance between the tip of the rectification
electrode and the burner is approximately 4mm.
Check it is angled so the electrode sits above the burner ports.
Carry out a resistance check between the tip of the
rectification electrode to the inline connector.
Resistance should be short circuit (zero resistance).