The Hypro Valve Repair Kit 2388 includes 6 valves and 6 valve o-rings. Hypro D403 Diaphragm Pumps are designed specifically to make regular pump maintenance easy and affordable. The valves are easily accessible without having to take the entire D403 pump apart, which means you can use Kit2388 to do the maintenance yourself. If your D403 is not drawing water or the flow is irregular than one or more of the valves may not be seating properly. You should check them for any debris that may have gotten in.