Set Appliance State:

Gas Off
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Mode Selector Switch to DHW position
Remove pump central inspection screw
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Observe pump central inspection screw.
Is Water Pump running?
Note:
Do not take noise or vibration as an indication of the pump running.