O have a one year old American Standard 'Low Consumption Water Closet'
(keyword = Low Consumption). The only somewhat readable ident info on
it is

9317-N
6.0 lpf/1.6gpf

I was working just fine until about two weeks ago. Now it does not
want to flush completely. I don't think my waste has increased
measurably, so it appears to me that not enough water is being drawn
from the tank to the bowl. In fact - the thing seems to want to do
the flushing action before the tank is half empty. I never noticed
that before.

I thought if I could get more water to the bowl that the flushing
would be increased, but I quickly discovered that even if I hold the
handle down (thereby emptying the tank), the flushing action still
occurs half-way through and the rest of the tank-water simply passes
through the bowl (rather slowly) out to the exit.

So I guess what I am saying here is that this toilet wants to flush on
half a tank of water no matter what. Can that be so?

I have tried shortening the draw chain (to the rubber whatever), and
reducing/removing/increasing the size of what looks to be a yellow
sponge float on that chain. I have even tried moving that float (if
that is what it is).

Am I stuck with this?

Help please