I have an older model trane xl 1100 and last year I replaced a bad board. A few days ago it stopped working. As I checked the board when I turned the thermostat up, the diagnostic light would go from solid green to-blinking 6 times. The attached card shows this to mean "Flame rollout switch (FL) open. What I don't know is how to test this, reset it or exactly where it is to replace it. The exact model of my furnace is YCX036F1HOAC, and the replacement board is an Emerson 59524-3. Any help would be appreciated and warming.