A running dual flush toilet is not your common red ball **** leaking at the base valve. This is easier! There is a silicone ring valve at the base of the "tower" that needs to be replaced. Instead of prying the old ball **** out of its little rubber hinge and dropping in a new one, this procedure is about as easy. FLUSH TOILET, turn supply off. Turn the " tower " 1/8 turn to release the bayonet type tabs and lift straight up. At the bottom you'll see a large silicone lip seal. Pull this off the piston and replace with Fluidmaster 83SGB at about $5.50. There are 2 gaskets in card, use the gasket that matches the ID of your old one. Mine took the smaller ID gasket. Stretch new gasket onto piston and make sure it's flat. Put tower back in and give it a slight turn to lock it back in, the 2 buttons should be inline with tank to match up with cover flush pushrods. Turn water supply back on and the bowl should fill and you should hear no more dribbling into the bowl. Well done! Total time...<5 minutes.