Look in ALL upper and lower corners and under windows for soft spots (dry rot). make sure all appliances work AC, stove ,oven,refrigerator. water pump,heater. If appliance works on propane and Elec. (refrigerator) make sure both systems work. Check date code on tires most suggest replacing at 7 years, could be a bargaining point. Nice if he has maintance records would be plus. does he still have all the manuals how things work? look down side for signs of delamination. Soft spots on floor, conduction of ceiling discoloration or soft spots. Floor plan you can live with. Seat belts for car seat?
