</font><font color="blue" class="small">( I have not seen any problems with the controller itself )</font>
Your cylinder diagnosis may be correct Chip, but my hydraulic controller had a serious leak between the controller body and the bottom cover plate. Steering control was erratic and inconsistent. Depending upon how much resistance the turning wheels encountered, sometimes it refused to steer at all. That said, the location of the problem was obvious due to the significant amount of hydraulic fluid dripping onto the bell housing. I cut a new bottom seal (gasket) by hand, applied proper torque on the bottom cover bolts, problem fixed.
But you're both right. It's a ***** of a place to get at.
//greg//