Hi All,  I know what you are thinking!  But please read on.

  It was the Night before Christmas and the toilet did run.
  I have been down this road before, and I know it's no fun.

I just replaced the toilet mechanism last year and now it was bad?
Knowing it was Christmas Eve I went into a panic!  I only have one
toilet in my house and the shutoff valve under the toilet was stuck.
I ran to the cellar and shut off the water to the house.

I then called my friend's hardware store, but I got no answer.
I jumped into the car only to find several local hardware stores
closed.  I tried K-mart but there was no parking.  It then hit me
that one of the hardware stores near my friend's store is open even
on holidays.  As I was driving to the store I went past my friend's
store and it was open.

As I went through the door several people called out my name!
I then said my toilet was bad!  From the back came a voice that said
"Hey! Call a plumber!".  It was Tom, our local plumber.  I showed
him the rubber diaphragm and he said, "That's fine, just flush out
the valve".  He told me to hold a plastic cup over the valve, when
it was apart and run some water.

I then said there must be more to this valve then the average toilet
valve.  The valve was running full out, unlike a slight clog.  I
mentioned what was written on the package of the Fluidmaster, how it
was a patented design and the water pressure helps shut the valve off,
but he said they all work the same way.

I bought a new diaphragm and went home.  I carefully looked the unit
over.  I was amazed at what I had found.  The float on the Fluidmaster
only moves a tiny thin metal rod which goes through the rubber
diaphragm.

At first it looked like something had broken in the unit.  I put on my
glasses only to find that the thin metal rod acted like a little valve,
which controlled the larger one.  A tiny clog in this little valve would
cause the big valve to stay open.

I then found a tiny little clog in the rubber tube that is molded into
the diaphragm.  There is tiny hole on the side of this tube.  The hole
through the diaphragm does not get clogged.  The one on the side of the
tube does get clogged.

As the float on the Fluidmaster toilet valve moves up and down it
controls a tiny amount of water that moves the diaphragm.  The diaphragm
then controls a larger amount of water.  The way the valve is setup,
more pressure only makes the seal better.

Now, as for Fluidmaster's patented design, I will only say, it sure
looks like somebody there owns a player piano!

John Conrad Kleinbauer

 [ I had the same experience.  The valve reminds me a bit of the vacuum-
 [ powered transmission assist servo on the 1948 Chevrolet, wherein a
 [ tiny moving pilot valve causes the big piston to follow the motion.
 [ This might make a fine design for a music roll tracking mechanism, John.
 [ Then you can write "Toilet Valve in Player Piano!"   :-)  -- Robbie