Irondragon, I will reserve the Mark Krause card until I have explored all other options. I met Mark at a CBA conference years ago. He was demonstrating a self contained power hammer that he built from hydraulic cylinders and valves as I recall it was amazing , my wife still talks about it . Frosty, once the hammer starts the tup will raise and stay at in the top of the cylinder at idle with no pressure on the treadle. The limit pin on the lower spool valve cap keeps the valves from turning too far . The valves may be mistimed and I have made an temporary adjustable link from a turnbuckle but will have to wait until I make new gaskets and reassemble the hammer to try adjusting the timing. Your description of the operating principles seems spot on, and yes the last sentence is what i am expecting . All parts have been carefully cleaned , wrapped and marked with location and index marks , not scattered on the floor . I still have all the issues of the furry freak brothers in a drawer somewhere . You can see the border from the top of the hill behind my house , I was in southern Alaska for a month in the early 70s loved it. Will be back someday. Swedlefiddle, I was out in the shop with a flashlight 2 minutes after reading your post , no extra hole in the piston , that would have been too easy Benona, I made an adjustable link from a turnbuckle and will test it when the hammer is reassembled.
Thanks you all for taking the time to respond , I will post the results of the re-timing of the valves .
Gerry