Arrived to do a performance maintenance. Set up for combustion analysis and static pressure tests. Found that the system is operating with failing static pressure. Reached out to a field supervisor to provide up to date pricing on static pressure repairs. Verified operation of all mechanical and electronic components in the furnace. Cleaned the flame sensor and retested its performance. Checked blower for cleanliness and to see if there is any play in the bearings. Found that the blower wheel is heavily coated in debris. Checked systems heat exchanger to ensure proper venting of flue gas. Found that the heat exchanger is heat stressed, showing hot spots. Checked for carbon monoxide in the air stream. Performed an electronic gas leak search. Spoke with homeowner about the system. Furnace is operational at this time.