i have a 1989 gas furnance with an electronic spark ignitor. now the pilot flame stays on even after the burners stop and the burners won't start after the first cycle. Initial start up works good and heats the house. the next time it doesn't work while the pilot flame has been on the whole time. i have to turn everything off completely and start anew before it works again...once. is something wrong with the ignitor sensor or the circuit board or something else?