Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
DHW temperature control to maximum
CH temperature control to minimum
Remove the vent plug from the pump.
WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure
Mains Power On

Observation:

Remove the vent screw from the front of the pump and observe the spindle.
CAUTION: Water may be emitted from the end of the pump, be sure to protect the work area while undertaking this test.
Does the pump run?
Note: Do not take sound or vibration as indication pump is running.