Complete 1 system furnace repair and preventative maintenance check. Left behind replacement filter. Tested mechanical and electrical components, found worn flame safety and ignitor. Recommend repair. Tested combustion and found good readings, safe co levels and good oxygen levels. Found current filter setup to be very restrictive causing high static pressure. Recommend pureairx electronic filter for lower static pressure and better filtration. The system is heating at this time. Installed pureairx electronic filter and upgraded tune-up to a maintenance plan. Customer used $50 coupon