Toto uses a couple of different fill valves, and the one you have is not made for them by Korky...sorry. As I understand it, that one is not repairable, and if it leaks, must be replaced. You do want one either made for Toto or one that is adjustable so that you don't waste water and get a good flush. Those made for Toto balance the bowl and tank refill so both just fill when the tank shuts off flow. Otherwise, you'll either end up with dumping excess bowl water down the drain, or not having enough water there so there's a lousy flush. Korky does make a generic adjustable valve that will work with any model and may be quicker to find than the custom one for Toto. That one has a little valve you adjust to balance the flow so both the tank and the bowl fill up at the same time...should only take a couple of minutes longer than a straight replacement to get it right after a couple of test flushes. I think there's a video on their website.