I just got off the phone with Camco and found that the spray flusher has a built-in check-valve to prevent backflow. I discussed the possibility of the check-valve breaking down and being the black particles in the lines that jambed the ports. 1-year warranty of course. Now for the good news. I found the valve on the Walmat.com website for $21 plus tax and shipping. You can order it to pickup at store (no shipping) or home delivery. Home delivery is shorter delivery time. The listing #40126 labels a Rinser and a Flusher,
they are the same. That saves about $20. Sure it come with all the other hoses and fittings, it is still less expensive.