As recommended in this forum, I replaced the valve unit and made sure all lines were clear. When I press the actuator lever with a cup, water enters the valves, flows in and out of the filter (new) but stops back at the valve, building up pressure and starting to leak. I suspect the valve to the water dispenser is not opening, but since it's a new unit, might it be the wires connected to it? If I replace the wire and diode, might that get the system working?