I have an old MTD tractor. It has an 18 HP Briggs & Stratton engine. When I try to start it, the engine turned, but crank very weak. I charged the battery overnight and fully charged. I got the same symptom. The engine crank week. I felt the cable on the battery, and they got hot. Is it possible that I got a short in the starter, or the starter just week? Anything else I can check?