Inside all Red Paddle Co pumps are at least 2 Non Return Valves. If your pump is feeling "bouncy" when you push down on the handle then you may need a new Non Return Valve. We recommend you buy two or more to ensure you always have a spare. How do you change the Non return valve? It's easy. All you need is a screwdriver. Use the screwdriver to remove the 4 silver screws that are holding the black or grey "cap" on to the top of the pump chambers. Then pull the pump shaft(s) all the way out of the pump. At the end of the pump shaft(s) you will see a white disc with a black O Ring around it. Just unscrew the white disc from the pump shaft (use a cloth to cover the area to stop your hands from getting messy). Then just poke the long end of the non return valve through the white disc and pull it out the other side so the barbed section is pulled all the way through the hole. Try and perserve as much of the grease on the white disc as you can. If you want to add more grease then choose Lithimum Grease. This can be purchased from most cycling shops. Then just screw the white disc back on to the pump shaft and reassemble the pump.