Upon arrival system was off. Set to heat. Inducer comes on and spark igniter sparks but no ignition. Gas valve is getting proper voltage. Hit gas valve as it got voltage to open and system ignited. Gas valve is sticking and should be replaced. Checked electrical, blower capacitor is out of spec. Recommend replacing. Performed courtesy safety inspection due to age of system. Heat exchanger is beginning to crack behind faceplate. Recommend upgrading system due to age (26 years old), efficiency, and cost of repairs. Set up appointment for system replacement for November 10th at 11am. System is intermittently operational