Repair for a Phelps Honey Wagon isn't difficult if you have the right guides. Our mission is to make this process as easy as possible. We've provided three easy to follow diagrams. The first is a diagram of the macerator pump. It is only found on the 300M model. The second diagram is for all the gas diaphragm pumps purchased from us before 2003. The third one is for all the gas diaphragm pumps purchased after 2003 and the upgraded electric pumps. If your pump was purchased in 2003, look at both diagrams carefully to be sure you have the right one. While there are three different types of engines used on these models, the diaphragm pump is the same. This guide is extremely helpful for maintenance and repair.