How do I perform a Kohler toilet flush valve replacement?

To perform a Kohler toilet flush valve replacement, first turn off the water supply to the toilet. Remove the tank lid and flush the toilet to empty the tank. Disconnect the water supply line and unscrew the mounting nut to remove the old flush valve. Install the new flush valve by following the manufacturer's instructions, then reattach the water supply line and turn the water back on. Test the flush valve to ensure it is working properly.