I have a true blue 90 tech 4 furnace, it has had off and on problems with the pressure switches, and the control board was replaced last year.
Starting last night only 1 of 3 burners is lighting, the burner closest to the pilot. The furnace ran all night long just to maintain 60 degrees.
Any idea what the problem is?

Remove the burners & if they have "wings" clean the slots in the wings with a piece of thin metal (a feeler gauge works well) then blow them out with compressed air (you an use the canned air you use on the computer keyboard). The wings carrry the flame from one burner to the next. Your burners may have small tubes with the end looking like they are almost pinched shut. These are somewhat harder to clean since they are smaller but use the same procedure or a piece of small diameter wire.