I have a 2 year old Lennox Winslow insert that will run from 15min to 2 hours then shut off with the red problem light blinking. I can restart again and it will do the same thing. I have cleaned out the side ports and all blowers, chimney, pipe ect. It burns really well when it is running. I did replace the proof of fire switch and that did nothing. I am thinking of replace the control board as what else could it be. I am afraid to have a tech come out and get it running only to shut down after he leaves. Any suggestions would be helpfull. Thanks