I have a Roper electric dryer, RES7745PQ0. It's about 3 years old. I set the cycle time and can hear the timer working. I hit the start button and the heat turns on but the drum doesn't spin and I can't hear a motor. No air is blowing besides what the heat is moving. I open the door and the heat stays on until I set the cycle timer to off. Can someone help me get started troubleshooting? Thanks