I have been reading the archives on how to set the proper height of the rear by adjusting the lever on my hydraulic valve box.

However, in moving my lever the system either raises the rear all the way to the top or sinks to the bottom - there is no inbetween setting, it is either going up or coming down even with the most minute lever arm adjustments.

Has anyone heard of the valve box failing in this manner ?

Should I attempt to rebuild the valve with the parts kit or is it wiser to replace the valve box at a greater expense ?