Set Appliance State:

Mains Power Off
Gas Off
Isolate Mains Power to appliance as per TOPs P4
Discharge and drain boiler
Remove wax capsule housing and wax capsule from the base of the diverter valve

Observation:

Using a screwdriver or other suitable tool push up the diverter valve spindle then release.
Does valve spindle move up and down freely operating the microswitches on top of the diverter valve?