Searching for why the oven will not get above 325 degrees, the cause could be heating element, temperature sensor, or inadequate ventilation. When I got the square element, it did not look like the broiler element. So, I called APP and spoke to Sylvia who graciously explained the heating element is below the bottom cover in the oven and two screws at the back corners hold it in place. She also mentioned the temperature sensor is at the top left (looking into the oven) and it is held in place behind the back panel. With this knowledge, I decided to test the temperature sensor first. Philips screw driver, remove panel. I have a multi-meter, but the sensor plug is two small for my multi-meter probes. I cut an piece of spare wire, stripped about 1/2 inch of each end, put that in the sensor plug, and the test prove sensor OK. The broiler element got hot so it was OK. Unplug the two connector from the back of the heating element, no continuity, and no Ohms. After removing the heating element, the back left corner was "burned through" so the fault could be easily seen. Replaced with the new heating element that did have 1080 Ohms at room temperature. Back together and working oven. It takes 15 minutes to preheat the oven to 450 degrees which is within the 12-15 minutes standard. A repair video would have helped, (found one on another site). Replacement was easy. Testing was not difficult. DO NOT FORGET TO UNPLUG THE OVEN FIRST. Also, do not use a MULTI-METER with the Stove plugged in - that is from the Multi-meter manual.