Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Remove the selector control knob
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Manually turn the selector spindle to its off position, refit knob and turn appliance back on to required mode.
Has combustion mode ceased?
COMBUSTION MODE CEASED
COMBUSTION MODE REMAINS