Isolate Mains Power to appliance as per TOPs P4
Remove the spark electrode assembly

Observation:

Thoroughly inspect the spark electrode assembly for damage, cracked ceramic and for correct spark gap.
Check the spark gap is 3.5mm ± 0.5mm.
Refit spark electrode assembly after test.
Note:
Before reassembly check the integrity of all disturbed gaskets and seals and replace as necessary.