Croppie,
We were talking just about the spanner, BTW its a hell of a price, £70.00.
Now that's a different thing, what you should do on a service is strip the burner down completely, only then can you be sure that the tube is clear, the fan scroll blades are all clean, the flame ring is clean, HT lead and electrodes are not cracked, cell is clean, the oil pump drive coupling and the plastic drive on the pump and motor are OK, so you don't need the key at all, what the key does is allow to take out the nozzle and do a runner.
If you are called to a burner that's not working correctly and you don't strip it down you will be back the day after.
I had 12 combustion engineers working for me back in 1970 and that's the only way I would have it, go to an oil burner job, your strip the burner down, all these qualification Croppie mean nowt if they can't cut the mustard.
Croppie, I have worked on burners with 10 ft flame length without all the certificates, 2 to 10 million Bthus