10/14/2015 10:10 AM
I would try draining the fluid and see what comes out. I would use Dextron V or higher as it will exceed all the others, and help it run cooler as well. When your setting/adjusting the cables are you using the fish scale and setting each cable to the proper pounds that Toro requires? You can try a fluid change and setting the cables to the right lbs if you haven't tried it yet. If that doesn't work then its time to go inside the trans. I had 04 and 06 models and there was an upgrade to the clutch cones for transport and mow. Also an upgrade to the sun gear that has an extra set of bearings in the middle of it for more support. I don't remember the specs as it was roughly 4 years ago since I was last working on one, but I'm sure you can find them on Toro's site or maybe you have the service manual.
Hope this is of some help to you.