Hi all, Here's a good stumper for you.....I have a client who has many Eng air DJ-100's on the his roof, unit was working fine until the burner motor seized (common problem with these turn down burners) Pick-up a new motor, wheel and magnet from Eng Air, replace everything keeping combustion air damper in same position with no problems. Go and start the unit, burner wont fire up because the pilot wont light....Good pilot pressure, good spark, pilot air tube clean. Put a new pilot assembly in same thing.....The only way I can get this to light up is to close the combustion air damper almost closed. This unit was working fine and had a perfect combustion analysis taken 30 days ago until the burner motor died 2 days ago, the new motor, wheel and magnet is the exact same from Eng Air. The unit goes through pre-purge no problem, magnetic sensor works fine to sense "light off speed" of combustion air motor...once down to "light off speed" pilot valve opens....good spark but fails to light. I have worked on these units for almost 10 years but this has me STUMPED.. Anyone ??? Thanks