Remove the three screws along the front that hold the bottom plate (the part where the filters and lights are located) to the oven and allow it to hinge down, but hold on to it so you don't pull out any wires. The turntable motor (AP3770128) is in the middle and should have a couple wires going to it. Us a multimeter to verify voltage (120vac) to the motor when a cycle is started. If you have voltage and the motor doesn't operate, then it is bad. If you have no voltage, then there is probably a broken or loose wire.