Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
Mode Selector Switch in OFF position

Observation:

Turn on HW tap.
Does DHW Flow Switch and Fulcrum Arm operate DHW Flow Microswitch?
Turn off HW tap.
Does DHW Flow Switch and Fulcrum Arm release DHW Flow Microswitch?
Note:
Remove the microswitch plastic cover (depress single plastic clip) to observe the operation.
Refit plastic cover after test.