Toilet won't refill without help

[mg21dg]

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?

 

[havasu]

The same occurs at my vacation home when there is not much usage with the toilet. For me, I learned the mineral deposits begin to stick to the vertical tube. Since the Fluidmaster 400A replacement is only about ~ $8.00, I just replaced the unit, and I'm good for the next few years.

 

[Caduceus]

I agree with havasu and to add to it I have found the Fluidmaster Pro45B fill valve to be well worth a few dollars more if it's available to you.

 

[havasu]

[ame=http://www.youtube.com/watch?v=F1klFYaBEd0]YouTube - TradePro FluidMaster Overview 90[/ame]

I've never seen these at my local big box hardware store but will give it a try when I find one! Thanks Plumb-Crazy!