Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove the spark electrode leads from the spark electrodes

Measurement:

Inspect the condition of the spark electrodes, they should be clean, free from any damage or broken ceramic and should be aligned as per the diagram shown.
Measure the resistance of each electrode from its tip to where the spark electrode lead connects.
Expected resistance, continuity / zero resistance.
Are the electrodes in good condition aligned correctly and is the resistance measured as expected?
Note:
Image shows electrode removed for clarity but test is carried in situ.