rived on site to perform maintenance on 13 year old furnace. Cycled system for heat. Verified proper heating sequence of operations. Temperature rise across heat exchange is within range. Ran system through 20 point inspection checklist. Gas pipe is not hard piped all the way out of the furnace and does not have a sediment trap. Also condensation lines do not have any condensation safety switches . Adding a 5 inch filter cabinet is not a option due to system set up. Indoor motor amperage is close to maximum, and motor has started leaking oil and there is a significant amount of dust build up inside blower compartment. Cleaned burner assembly. Washed filter. Went over findings and recommendations with homeowner. Want to hold off on any repairs. System operational upon departure.