Did I prevent an im tenance on the Lenox 80% unit. Did a combustion test Seo level was 2202 level was 12. During the maintenance I clean the flame sensor also cleaned out the burner rack and blower motor housing. Also did amp readings on the inducer motor and blower motor service or within range of furnace specs. Part of the chimney was falling apart where the flue pipe meet the wall, I used silicone to seal the gap. Also switch the 16 x 20 x 1 filter. System is operating properly at this point. M#G60UHV-36B-090-07 s#5907K30440 customer prepaid