I have a Tappan electric range that is at least 10 years old. Something seems wrong with the electronic board and buttons. I can't get the oven to bake or broil. Also, I can hear a fan running when I close the door. I've tried turning off the breaker, hoping the oven would reset. If I press bake, the temperature indicator comes on for a second, but goes off before I can select a temperature. Also, sometimes the word "locked" appears, also just for a second. The burners are manual and are working just fine. I can't find the owner's manual, even after searching online. Any ideas what the problem is?