Place an oven thermometer in the middle of the oven cavity. Set the oven for Bake at 350°F and start it. Wait until it's preheated (should beep). Give it 15 minutes more. Open the oven door and read the thermometer. Post the results.
- The oven thermometer
Part number: AP4022061 
Gene.
P.S. The model number you posted is incomplete.