In the past week, my toilet has stopped refilling by itself. Here is a diagram of what I have in my tank: The float - as in the diagram, it's a cylinder that slides up and down the valve body - somehow is not dropping with enough force to trigger the refill. It seemingly goes all the way to the bottom as the tank empties, but there is just a barely-audible trickle of water into the tank. If I manually push the float down, nothing happens. But if I lift the float to the top and let it drop in an empty tank, it immediately triggers the refill, and the tank fills fast. Can't find any obstruction on the valve body, and I can slide the float up and down the valve body and it travels smoothly. But the only thing that forces a normal refill is lifting the float in an empty tank and dropping it. Putting downward pressure on the float does nothing, nor does jiggering the arm at the top of the valve body. Any ideas what's going on?