Furnace tune-up and safety inspection. Cleaned all sensors. Tested gas valve voltage and inlet/outlet pressures. Found multiple issues. Corroded ignitor and flame sensor. Changed the very dirty furnace filter that the customer provided. Because the filter is dirty, the blower motor has overheated at least once, and oil has dripped onto the undercarriage of the blower housing. The blower motor capacitor is also outside the acceptable range and needs to be replaced. Also found the flue pipe had rusted through an elbow joint, allowing fumes to leak into the home. The furnace is from 2004. Giving customers multiple estimates for repairs and/or replacements. The customer will still have an AC/spring visit remaining on the VIP service plan. Performed free plumbing inspections.