how to rebuild valve that selects hydro power from front bucket to Backhoe

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I bought a ford 3400 tractor with an arps 730 backhoe and the valve that diverts the hydro fluid from the loader to the arps backhoe is stuck. The previous owner did not run the hoe much so the valve is stuck in loader position. The valve has model number s-75 and part number 1120. If anyone can shed some light on where I can get a rebuild kit or manual or even a web site for this valve that will be better then going blind trying to rebuild this with no specs. Thanks.