How does the factory check the baking temperature control on an oven?

Our oven seems to erratically heat in the baking mode. Sometimes it is too hot, sometimes it is not. Food can come out burnt or not cooked for several hours. I replaced the temperature sensor. I want to do a test to determine if the oven is calibrated properly. What [...]

How do you check the proper themostat operation in an oven?

We have a Kenmore electric range, an oven. When we set the cooking temperature to a certain temperature, say 400 degrees F, if we open the oven door and the oven temperature sensor is in the upper right hand section of the oven, where should we point the digital thermometer to read this 400 [...]