I have a Carrier furnace that has been reporting errror 34 (ignition proving failure) and error 14 (ignition lockout). Sometimes it works and sometimes it errors out. If I disable power for a few minutes, it will usually work. Looking in the burner box, I noticed that 3 of the 5 burners work solid. The left most 2 seem to flicker on and off. If I remove the burner box cover, all 5 burners work solid. Any thoughts on what the problem could be?

My only thought now is that the flame that lights the burners one after the other is some what blocked between burner three and four. Turn the gas off and try to vacuum out that area and see if it works.

Also if the flame sensor is dirty it will make the flames do funny things. The sensor can be cleaned by taking it out and sanding it with some sand cloth or sand paper.