Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect the speed control
(right hand plug) from the pump
Disconnect X23 from the PCB

Measurement:

Measure the resistance between pin 1 (brown)
and pin 2 (blue) at the disconnected plug.
Resistance should be open circuit.