The fuel gauge in my tractor has stopped working. When it was working, it would stay at empty until the tractor move around some, and then it would give a correct reading. Now, the needle is pinned at the far end of empty, so I am inclined to think a broken wire, or a grounded wire, depending on how the gauge works. What is involved in getting to the sending unit, and tracing the wire back to the dash? Do these series of tractors have a history of problems with the sending units? thanks