I bought a Ford 851 from a guy, and the power steering does not work. He said someone worked on the steering column unit but it still did not work. The tractor has a good power steering pump delivering plenty of pressure to the steering column, but no power goes to the hydraulic cylinders. I took the column unit apart but I could not see anything wrong. I did notice that it could possibly have been incorrectly reassembled, as there are several parts that could go one way or the other. I cannot find a detailed breakdown of the correct assembly for the unit. Can anyone help with this?