[concessionstandman]

I operate a school concession stand (and am a teacher at the school, too) here in Minnesota.
I've got a Baker's Pride commercial pizza oven--2 slots, 3 elements, it's lined with a ceramic tray for the two slots.

Here's the trouble:
About one hour into the evening (cooking 2 pizzas every 25 minutes or so), on about the fifth pizza, they start to "not get done." No matter how long they are in the oven, they are doughy on bottom and the cheese begins to burn! Could I be tripping a high limit switch that resets after it cools down?

I am somewhat mechanically inclined and can follow simple testing procedures with a multimeter.

Today at school I brought in an oven thermometer. I fired it up to 400 at lunch and checked. One hour: held fine, right on 400. Two hours, right on. Three hours, perfect 400 degrees.

What could be going on? Is it possible the rapid turnaround of door open, new pizza in is causing problems? Any hints or ideas are welcome!!

Thanks