The first problem I was working on was that the Lower Blower was not turning so I opened the back of the oven and gave it a push. It started working but I knew that I would need to replace it. I reassembled the oven and realized that the oven wasn't heating. I got on the "Appliance Parts Pros" website and used their troubleshooting topics and videos and discovered what had failed (Thermal Fuse). I disassembled the oven again and tested the thermal fuse by placing a jumper across the fuse to prove the failure (the videos show you how to replace parts not how to test the parts for failure). I only used the jumper to prove the failure, I did not operate the oven with the jumper in place after the test was complete. I purchased the parts from "Appliance Parts Pros." they arrived 2 days later, I changed them out (they fit perfect!) and now my oven works great!