I removed and disassembled my Tuff Torq K51B transmission. The first thing I noticed was that the blades on the fan were missing. The transmission was dirty as all get out. After opening the case I found there was no metal fines in the oil. I was black as coal but didn't smell burnt. The gears were a sharp as new and showed little if any sign of wear. I removed the pump/motor assy and there is no sign of wear on either the pump or the motor. no scoring or unacceptable wear side to side on the pistons in their cylinders. What I did find is that the inner housing is scored were the base of the pump motor rides against it. A new inner case is only available with a rebuild kit that is almost $600. Has anyone else encountered this problem? I plan on trying to remove the scores using progressive grades of sandpaper. Any suggestions on how to proceed? Has anyone done this before?