Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect spark electrode lead from spark electrode

Measurement:

Visually inspect the condition of the spark electrode for cracks and/or damage.
Carry out a resistance check between the two ends of the spark electrode.
Resistance should be short circuit (zero resistance).
Note:
Electrode shown removed for clarity, test can
be carried out with the electrode in situ.