Update:
1. ovrszd is correct - it was not a DEF issue. I apologize for not posting another photo. Somehow I missed your post. The piece was from the starter.
2. I called the dealer last Monday. He sent his mobile crew out. They identified the problem as the starter. Apparently there is a service bulletin out about the key switch sticking and burning out the starter.
3. It was under warranty, and they had the new starter and key switch installed on Friday. They ended up leaving the headlights on by accident and draining the battery, but once I figured that out and charged the battery the tractor is running perfectly again.
4. Thanks to everyone for their input on this.
Bob