What is the proper procedure for cleaning a oil furnace, such as cleanouts to heat exchangers and where could I find a exploded view of a lennox oil funace

Don't Know About The View.. but One Must Find Any And All The Cleanouts And Do That... clean Em Out. Properly Seal Them Once Done. Remove Smoke Pipe Then Brush Out And Clean Out Chimney Base Too. Then Do N-of-pg... oil Motors And Such. But With Out Tools You Won't Be Able To Set Burner Up To Peak Eff.

n-to-pg ?

Sorry.. nozzle.. oil filter.. pump gasket