Press down and hold the handle on the multi-valve pump’s diverter head. Locate the small pin at the base of the handle and press it out with the tip of a small Phillips screwdriver. Lift the handle off the diverter head.
Locate the valve plate on top of the diverter head and remove the screws that secure it, using a screwdriver. Pull the valve plate off the diverter and set it aside.
Pull the diverter out of the pump. Keep the diverter shaft's O-ring and spring. Remove the spider gasket from the shaft.
Clean the bottom edge of the diverter with a rag and check it for smoothness. If it is not smooth, the diverter is defective; if it is smooth, the leak was caused by a faulty gasket.
Apply gasket lubricant to both sides of the replacement gasket. Slide the replacement gasket onto the shaft of the diverter.
Place the diverter back into the pump and secure the valve plate onto the pump housing. Place the handle onto the diverter head and press the pin back into place.