Wallstar 12/14 Boiler with Electro Oil B9 burner locking out

[Sutchie]

Hi, I am having problems with the boiler installed in a bungalow we have recently moved in to. The burner is an Electro Oil B9 with a Danfoss 0.5USgals/hr 80oH nozzle. The problem is that we have to manually reset the boiler several times during the evening and each morning. It starts first time after the reset with no problems. This is my first experience with oil burners and I have just had the burner off for inspection and found the electrode set-up/placement quite different to the details given for a similar burner used on the 12/15 model (Stirling 40) and I cannot set them properly as the nozzle face is only a couple of mm away from the diffuser disc and so the electrodes are closer to the diffuser than they are to each other. Also there was quite a build up of 'stuff' (a cross between Weetabix and kitty litter and not sooty at all) between the back of the silencer box and the back-face of the heat-exchanger, probably sufficient to cause some obstruction to the flue gas flow. When we bought the property the vender said that the boiler had been serviced 'about a year ago' but no proof available and I assume from the various build-ups of kitty litter and soot that this potentially not entirely true. Everything is back together now and the burner actually sounds quieter (possible wishful thinking), but it keeps whooping and although the frequency of resets required is less, they are still required. Any ideas on the kitty-litter/Weetabix mix, has something collapsed/disintegrated

 

[Burnerman]

Is this the one with a BFP 41 L3 oil pump by Danfoss? Replace the coil on the top of the pump, or at least take its resistance at time of failure.....notorious for packing in. I think its part number is 071N0051.
John