I am looking at a 782D to purchase, but it has ahydro problme. When it is first run, the deck and trans operate normally. When it gets hot the trans will work when under a load, but will freewheel when not, and the deck will not move. It has had a fluid flush and replacement with a new filter. There are no visible leaks and the valves on the Hydro have been swapped with a known working unit. He wants to sell the tractor, but I need any help I can get to see how much it may take to fix before I give him, an offer. Any help would be appriciated. Sorry for the long read.