Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Preheat OFF
Remove diverter valve motor and place in a safe position.
To remove - Place screwdriver as in picture then twist
anticlockwise to unseat diverter then pull out
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Inspect the diverter valve motor, does it move to the fully extended position during a heating demand?
Note:
New and old styles operate in the same way for this test.