I replaced the igniter 1st as it did not glow and as I understood the operating of the system Gas would not flow if it did not. Replaced the old one but still no glow. I later went on this sight and watched tests of other involved components and followed them. The thermal switch wire connection crumbled as I wiggled the wire to test. I replaced both this and the other sensor on the gas for good measure (reasonable priced why not?) Worked like a charm. Lesson for all, insist loads are kept to factory recommended and CLEAN the lint filter each and every time!!