On my ZD-221 (Pro deck), I move the handle to engage the PTO and blades and it does not engage. I checked the fluid level and it is at the proper full level. I checked the linkages and it seems that the rod that is attached to the handle rod is so hard to engage that I have to beat on it with a hammer to make the blades engage. The rod that goes rearward to the top of the PTO is the one that will not hardly move, even beating on it with a hammer. Additionally, when I want to disengage the blades, again, I have to hit in the linkage to make that happen. What could possible be the issue? I guess I should also point out that this mower has always been outside as I do not have a shop to keep it in. So, it is exposed to the elements year round. (NOTE the rust on the rod where it has been hit with the hammer)