Today we performed two system home care client replaces all medias. Cleaned all flame sensors, fuel rails and inducer ports. Checked gas pressures and inspected ductwork on basement system found no return. Inspected all electrical components and connections, replaced run capacitor for main level. Performed safety check on both furnaces with digital camera. Inspected heat exchangers on second level found severe metal fatigue and hot spots. Heat exchanger is compromised and could fail at anytime. Cycled equipment from thermostats checked all operations and left equipment operational. Scheduled install supervisor to give options on updating second level furnace and adding return in basement.