Help, I have a comfortmaker natural gas fired furnace that just keeps cycling. It does light but then cuts off and cycles again and again. I suppect the problem is the flame sensor but I cant find it. The book shows the location of it next to the ignitor and pilot but there is nothing there but the ignitor, and the controller box isn't even labeled for a sensor wire. The controller does say it is a continuious retry model, does that mean it doesn't have a sensor? The furnace model is a ntg3075hfa5, and the controller is a honeywell s8600m.