Spot-free systems are usually pretty basic, especially older ones like Futura's. If you can't figure out, you can always gut and replumb it. I worked on an older Water Lover's RO system that someone had plumbed so wrong that when it flushed it dumped all the reject into the product tank, so I took every hose and fitting off and redid it with a partial reject recirculation. It's nothing more than a loop from pump to membrane and back with a tee for water in from the solenoid and another tee for reject flow with valves to control recirc and reject flow.