fire not drawing?

fire wont draw chimney been swept today throttle plate clean thermastat opens and closes ok air wash has to be on minus or smoke comes into room when on plus all seals on door/draw new only thing not done is air wash not been took off and cleaned recent new set of bars had this boiler bout 6yrs and other than general maintenance cost been ok ..its a arrow stratford tf90

john horley
October 2015