You also seem to have ignored the point about the oil pressure.
Although measuring that is less relevant if you are using a flue gas analyser.
Is there a way to measure that pressure without a meter of some sort?
And is that necessary if the nozzle is the same as the one which was removed?
No ........... its not necessary .......... Thats why we keep going on about it!!
FFS ... It will cost about £100.00 to get your boiler serviced and with your attempts you could be damaging a perfectly good boiler