CO 5 ppm, O2 10%. Gas valve falls to 0 ppm on shutdown. Brushed burners. Blew out all drain traps. Tested condensate pump. Replaced cracked and brittle drain line with a new piece of clear poly. Burners are clean. Blower wheel is clear, but a little dusty. Used brush to wipe away loose dust. Water on the ground in crawl is from the previously mentioned drain line that was replaced. System is functioning normally. Reset temp to 69 before leaving.