Set Appliance State:
Set Multimeter to Continuity 
Isolate Mains Power to appliance as per TOPs P4
Measurement:
Remove and inspect the electrode and lead.
Ensure the ceramic is not cracked.
Measure the resistance between the
ends of the electrode and lead.
Resistance should be as below.
Original Lead: Continuity (zero resistance)
Modified Lead: Approximately 1.2kOhms
Ensure the ceramic is not cracked.
Measure the resistance between the
ends of the electrode and lead.
Resistance should be as below.
Original Lead: Continuity (zero resistance)
Modified Lead: Approximately 1.2kOhms
Isolate as per TOPs P4
and refit as necessary