New summary of my position
1) When the boiler is switched on there is a brief burst of activity and then after about 30 seconds it stops and the outlet pipe becomes warm. The pump continues to make a sound
2) While the boiler comes on there is quite a lot of noise from within the boiler, but also from the pump, I think I can hear air, so I am not sure if the air from boiler os making the pump make a noise.
3) I have checked the pump is rotating, by unlocking the octaganal nut, although as I said, it took several prods for it to get to full speed. The pump usually starts promptly. Can a rotating pump not pump?
4) The Honeywell valve does not behave correctly when power removed, as described in the video, when the manual open lever is moved to manual, it should offer resistance and should spring back, it does neither. I have managed to go to a plumbing shop and play with a new valve and it behaves as described in the video, and unlike mine.
5) I decided to see if the pump was pumping stuff around the CH circuit by opening the radiator bleed valves, there was no difference with the system completely off. This was while I could hear the pump rotating. Could the valve have closed the CH option, so no water was flowing.
6) While the pump is throbbing, the outlet pipe of the boiler is hot, but the the water next to the input of the pump is not, some 5 feet away, the pipe on the exit of the pump is quite warm, as though the pump is heating the water, it is very hot.
7) The problems only started when I switched the CH on.
Oilhead thanks for the suggestions, I will check the fault finder in the boiler manual which was hidden away. As I say, after prodding the pump knob did rotate at the proper speed, so can it rotate without pumping? Or can the impeller break from the spindle?
Daveydub
If the boiler has not been on for a few hours, which is now almost all the time it
1) Fires up, lots of fan noise and light comes on, the pump starts, then there is a gurgle and the sound of bubbles coming from the boiler which is immediately replciated by the pump. The the boiler heating light goes out, the outlet from the boiler becomes hot, and the pump continues, but the hot pipe sensation never reaches the pimp some 5 feet upwards, my boiler is on the ground floor, the pump is in the airing cupboard directly above.
This is driving me nuts.
I have evidence the pump is working, the rotating knob and the noise and I have evidence the pump isn't working ( no water from radiator bleeds, though this may have been caused by the honeywell valve refusing to open the CH circuit and that hot water is not making its way from boiler outlet to the pump.
And I have firm evidence that the Honeywell valve is not behaving as it should ( refusing to return to auto and no resistance to moving lever to manual )
I will check out the troubleshooter for the boiler as suggested by oilhead which I hadn't considered before.