Isolate Mains Power to appliance as per TOPs P4
Observation:
Remove the Diverter Valve Motor Unit from the Diverter Valve.
Can the Diverter Valve be set in its CH position by manually rotating its spindle?
Can the Diverter Valve be set in its CH position by manually rotating its spindle?
Isolate as per TOPs P4
and refit as necessary