Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove the connector from the spark generator

Measurement:

Test 1:
Measure the resistance between the 2 terminals of the spark generator.
Expect a resistance of 1MOhm or greater.
(O.L is acceptable because this is greater than 1MOhm)
Test 2:
Measure the resistance between one of the terminals and a suitable earth.
Expect a resistance of 1MOhm or greater.
(O.L is acceptable because this is greater than 1MOhm)
Are the resistances measured as expected?
Note:
Spark generator is shown removed for clarity but the test can be carried out with it in situ.