Set Appliance State:
Gas Off
Set Multimeter to Resistance 
Isolate Mains Power to appliance as per TOPs P4
Discharge capacitor to earth before carrying out test
Remove the blue and brown leads from the capacitor noting their locations
Discharge capacitor to earth before carrying out test
Remove the blue and brown leads from the capacitor noting their locations
Measurement:
Measure the resistance across the exposed terminals.
Resistance should start low then steadily increase.
Reconnect leads after test.
Resistance should start low then steadily increase.
Reconnect leads after test.
Isolate as per TOPs P4
and refit as necessary