Having just installed one of these yesterday, maybe I can help you out. The flush valve is one big flapper that goes up when you push down the lever. The valve is guided up the overflow tube with a semicircular cutout. It seems to be about 3 inches in diameter. It has a chain hooked to the top of it which goes to the flush lever arm. When the lever is pushed the chain pulls the valve assy straight up the tank dumps in a couple of seconds and flushes the toilet. Try holding the lever down for a few seconds when you flush.

The first thing i would do is check the water level in the tank. According to what is marked in the tank, the water level is to be set at 1 inch below the top of the overflow tube. check the water level and adjust the fluidmaster float so it is at the 1 inch point.

then check the slack in the chain. Make sure it has very little slack. just enough for a little play.

Then with the lid off observe the operation of the flush valve. When you push the lever and hold for a couple of seconds, all the water should leave the tank. If it flows slowly, I would think there is an obstruction between the tank and the bowl.

Next thing you will have to do is remove the tank from the bowl. @ bolts hold that to the bowl. First shut off the water and flush to drain the tank. On this toilet there still be water in the tank. bail out and sponge or towel out whats left. Get yourself a deep socket, I believe a 1/2". crawl under the toilet and loosen and remove the 2 nuts on the bolts. you will need someone holding a screw diver on the heads in the tank. Remove the nuts, and the tank pops off. There is a gasket between the tank and the bowl. The passageway from the tank to the bowl should have a plastic liner. Check that for obstructions.

I cannot see what else would cause problems.

The toilet does flush. The problem is sometimes when you push on the lever, its seems that it's not attached to anything and nothing happens. Sometimes you have to push down several times for the thing to catch.

the arm is connected to a chain which pulls up the large stopper/flapper. maybe the flush arm is not connected to the flush handle properly and is slipping. Get AS to send you another flush handle and arm. Take the toilet tank lid off and see if the arm raises if the handle is pushed down.

When the handle is pushed, the arm goes up, the flapper opens and the toilet flushes. simple as that.

Water keeps running after flush and does not stop completely. You can hear the water dripping all the time, then all of of sudden, it will sound like it is filling up again.

I also bought 2 AS. Cadet 3. One needs to to have the bowl replaced. As per AS. Tried everything else.

I have gone through all this too, it is the toilet bowl....never heard of this happening before.