Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Remove the diverter valve actuator from the diverter valve body

Observation:

Check for free movement of the diverter valve spindle.
It should be possible to depress the diverter valve spindle by finger pressure.

Note:
For clarity the graphic shows the valve
removed but it is possible to check the spindle
with the valve in situ and the actuator removed.