Could this be Steam Boiler or the Oil Burner's problem?

Hi (just a homeowner here),



In a nutshell, our roughly 40 yr old Peerless steam boiler, keeps shutting itself down but it starts right up when I wipe any oil residue off the oil burner nozzle (and also hit the red reset switch on the burner).



A little more detail, so had a new guy service the boiler before the start of the season - and to be upfront he's a great hard working "kid" in his early 20s and definitively knows what he's talking about but maybe he doesn't have as much experience with old systems like ours.



So, when he serviced the boiler by changing the oil filter and burner nozzle/filter the one thing I noticed he did was he saw the valve on the incoming oil line to the burner was turned way down (meaning small amount of oil allowed to come through) so he opened it up all the way fired up the boiler and everything looked fine. With the exception that he noticed there was alot of afterburn (flame still on) when the unit turned off. He said that might be an issue but everything seemed to be working fine and I mentioned that in the last 10 yrs that we owned the house I seem to remember it always run like that.



1st few wks - roughly every 2-3 days the boiler would not be able to ignite the flame. I remembered what he described about the afterburn - stuck my hand inside and wiped the nozzle - and presto the burner lit no problem.



next few wks - it got progressively worse meaning it would happen more often = 1-2 times/day.



He came back out and swapped out the fuel unit on the burner - thinking that it was doing it's job cutting off the flow of oil quick enough. He also switched out the connected piece which includes the line/nozzle/electrodes. Unfortunately, it didn't work and I was back to cleaning the nozzle a couple times a day.



So, I thought about his original visit and remembered how he opened up oil line valve (incoming to burner) as the only thing he really "changed". So, I closed it off maybe 3/4 of the way and it worked without any issues for a solid 5-6 days!



Then all of a sudden it was back to the same old routine. Ughh



Sorry, for all the details but I'm thinking there might be a hint in there that someone may recognize as the problem. Please help - there was no issue before and this seems like it can't be that complicated of an issue but obviously somehow it is.