I have a sears lawn tractor that is ten years old with an automatic transmission. The last two years the transmission losses power after ten minuts.It will move the tractor on a flat surface but on any inclines it stuggles to make it. Ive replaced the drive belt and also cleaned the cooling fins which helped for a short time.The tractor has a 15.5 kohler engine and the last thee years I plowed snow with it. HELP

Hi,
Generally the hydro units are not field-serviceable. I could look it up at Sears(or you can) if you supply the model number.
Peace,
Clarke