Thanks for the follow up. Even flap valves don't last that long. The newer silicone ones last longer but it isn't unusual for them to wear out in a couple years, especially if you use in tank chemicals to keep your toilet clean. Not sure they even sell 2000 Flushes anymore but that product was really hard on rubber tank parts. The blue and green tablets were really good at causing lazy flush because they became viscus in the tank, especially on seldom used toilets like guest bathrooms in empty nester's homes. I don't use any of them, but I make sure to use our hall bath every couple of days since the kids have grown up and moved out, just to cycle the water.