Hi all. I have a snapper z-rider model ZMT2500KH that only drives on one side. The other side seems to be in "freewheel mode" all the time. In other words, The right drive motor will freewheel only when the hydraulic bypass valve is opened, but the left side motor freewheels all the time. The left side does not drive when the engine is running. Does anyone have experience with this problem? Hydraulic fluid levels are good for both drive units. The right (working) motor has a cooling fan, but no shroud. The left (non-working) looks to have all the blades broken off of the plastic fan, and also no shroud. Signs of seeping are on both motors, but nothing to get worried about in my opinion. I am experienced with auto repair, but not too many cars have hydrostatic drive motors. Can anyone guide me in the right direction for diagnosing the problem?