Press down on the Vari Flo valve's handle and hold it in place. Tap the small pin seated in the handle base using the screwdriver. Once the pin is removed, gently release the valve handle and pull it up and off the diverter head.
Loosen and remove the screws set into the top of the Vari Flo valve plate. Pull the top plate off the diverter and set it aside, noting the orientation of the filter settings on the plate. Pull the diverter out of the valve body. Keep the small shaft O-ring and spring on the diverter head, but remove the spider gasket off the bottom of the diverter.
Clean the bottom surface of the diverter and ensure it is smooth. Lubricate the replacement gasket with the O-ring lubricant and press it to the bottom of the diverter. Place the diverter back down into the valve body. Do not lubricate the gasket with vasoline, or the gasket will melt and allow leaks.
Place the valve top plate onto the diverter and secure it using the screws and a screwdriver. Remember to place the top plate onto the diverter in the same position as when it was removed.
Place the valve handle onto the diverter head and hold it down by hand. Insert the small handle pin into the handle and tap it into place with the screwdriver.