I own a Maytag Gemini electric range that is 5 years old. The other day my wife said that she baked a cake and it fell. We tried three others and they didn't come out well either. The top oven seems to work fine. It holds the correct temperature while baking, according to an oven thermometer I'm using. The lower oven temperature, using both convention or convection, is off by around 50 degrees. What could be causing this in the bottom oven and not the top? Any help will be greatly appreciated.