Black smoke from oil boiler flue

[hr21]

Hi All,
I have noticed today some black smoke coming from the boiler flue, it was fine before this.

Had a new burner motor fitted in October after it came on whirring, but no other issues.

Was last serviced in February 2020.

Any ideas/ advice on what to do?

 

[Burnerman]

The burner needs a flue gas analysis taken, and the oil pump pressure checked. Unfortunately expect some sooting up inside the boiler flue ways at the same time if this has been going on for a while.
I assume there hasn’t been any fiddling with the boiler and all air intakes are clear?
John

 

[BoilerBob]

Needs a good service. Bob