Took a peep at the boiler last night. The "wet bit" of the divertor valve is just fine but the Synchron motor inside the actuator has moments of seizure where the gear can't be turned either direction, then moments later it frees up.
So..... Boiler suppliers don't have one in stock. The standard one that seems to be available for regular 3-way valves (from wickes, screwfix etc)don't seem to have enough shaft poking out of the gear.
Is there somewhere I may find such a beast. The numbers on the side are 660F 230V 50HZ 5W 5RPM 38903R-6-121-130 0328 The gear shaft sticks out 8mm beyond the end of the gear (for locating into the plastic housing)
Cheers Pete