Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
DHW Demand
Gain access to PCB
Remove right hand wire from Spark Generator and place so it rests above the terminal
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Allow boiler to run.
After fan runs can sparking be seen at PCB to loose wire?
Note:
Stand well clear and DO NOT hold wire in place.