Was using tractor moving dirt for an hour with no problems. While moving slowly, tractor stopped moving but engine stayed running. Went back 30 min later and tractor moved 30 feet and stopped again. After stopping second time, checked hydraulic fluid and added very little and it looked fine. 40 minutes later, cranked again and would only move in reverse. Went about 200 feet in reverse before it stopped again. This time when when I tried to go forward, it sounded like metal grinding. Left it over night. Cranked it up today and started moving again. Went forward about 100 ft and it stopped. Backed up 150 ft and it stopped. Now it is sitting. Whatcha think? Any help would be greatly appreciated!