Haven't worked on a Ford for some time, but I doubt you have cables controlling the valves from the control levers. You more than likely have linkage. You need to remove the covers for the backhoe controls and start checking you links for free or binding movement. Simply remove the pins that connect the control links to the valve spools. Now you can check if that control lever and link works freely. If all is well there, you probably have a problem with a control valve. It could be a bent valve spool, could be a problem with the centering spring assembly attached to the opposite end of the valve spool. You should be able to remove the caps of the centering spring assembly and inspect spring components. Check these things out and let us know what you find.