Well, it seems to be time to updeate this thread.
I got the mower working well just in time to break it.

I mowed a strip along my drainage ditch and pulled the mower in to turn around and go back to make another pass. When I did I smacked the valve assembly with the mower head. No visable damage to the outside, but it wouldn't turn the mower on any more. I pulled it apart tonight and here is what I found.
The first picture is what the top of the valve spool used to look like and the second is what it looks like now.
View attachment 170630 View attachment 170631
The top of the spool snapped where the pin goes through it. As parts for the valves are no longer available, I'm going to see if it is possible to get it welded. The alternative is to replace the entire valve stack assembly.:ashamed: