Hello. I'm having a problem with my Trane XL80 heater. After the ignitor lights the burners, sometimes the burners will blow right out and start again for a total of five times. Then the system shuts off, no heat. A friend tells me the sensor(?) needs to be replaced. This sensor looks like a thin spark plug with ceramic around part of it (for insulation). A screw holds it in place. Should I just take it out and replace it with another? It looks easy enough, is that all there is to it? Thanks, larry.