Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Boiler CH thermostat to maximum
Boiler DHW thermostat to minimum
Remove diverter valve head from the body and place
in a safe location - do not disconnect it electrically
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow fan to run and the boiler to fire with a CH demand.
Is the spindle fully extended as shown?