Here is another that you may or may not find helpful: the Flow Control Valve, or Pressure Control Valve, located under the right footrest, which you have to remove for easy access and also drain your hydraulic oil. This was an sob to get that nib off, and I had to eventually remove the whole thing. Notice once I got the nib off and the valve out, the O ring that was in pieces at lower middle 2nd pic. Also, where the pipe cleaner was going in to clean the port--that has an O ring that you place there after you get the whole thing cleaned up and are going to reattach to the tractor. Make sure you put a dab of grease on that spot to hold the O ring in place. Finally, the nib on the tractor which is helpful to remove and clean up, takes two new O rings to make a nice tight fit when you put the unit back on. Your configuration may not be the same but the principle is. My guess is that Tx Jim is right, you need to pull the Rockshaft, but doing these valves does not go astray.