Arrived on site to perform heating maintenance on 35 year old Coleman furnace. Met with Daughter, homeowner not on site and only available through phone. Cycled system for heating. Verified proper heating sequence. Temp rise across heat exchanger is within range. Unit was extremely filthy inside. Washed off filter pad and replaced both filters. Completely wiped down blower and heating compartment. Secondary motor control for indoor motor is weak and should be replaced. Blower motor is leaking oil and over amping. Unit cabinet is not sealed correctly and unit is leaking a lot of air into the bottom of the house, causing the air flow inside the home to be extremely weak and system is very inefficient. Spoke to homeowner over the phone went over system findings and recommendations. Wants to hold off on any Repair work for today. Unit is more than doubled its lifetime expectancy and parts on it are getting worn out. System is operational upon departure.