I have bosch valves on my tractor, with mechanical hook up into the cab, cables. Until now everything worked as I needed. Pull the handle either way, the cylinder responded, but the handle had to be held to keep the fluid flowing. Now, I need continuous fluid, but the handle keeps popping back into neutral. Fortunately, a friend showed me how to solve that by taking out the spool, taking off the top, and adding a few thin washers, be careful not to lose spring or ball. Adding washers prevents the pressure from popping the spool into neutral. But it only works one way. The handle still pops back into neutral the other way. Any thoughts on such a complex matter, for me at least. The valves are fascinating I must admit. Who ever thought those up?