We have installed an american standard duel flush toilet that uses a fluidmaster valve. Problem! The refill tube is mounted on a float attached to the overflow pipe. When the toilet is flushed the nozzle that the refill tube is attached to lowers with the water level, as the tank is refilling the refill line sprays water at the overflow pipe splashing around the inside and up onto the tank lid saturating the flush push button mechanism , also running down and dripping on the floor. Is this a common problem, or is something not setup correctly. Mike Elliston

Depends how old your toilet is, it may be a calcium build up problem on your little inlet pipe inside your tank, but first check your water shut off valve on left side of your toilet near the wall....It may not be open all the way OR the valve has an issue...

these are called phantom flushes. the water is slowly leaking around flapper or the is a scratch of the flapper seat. I use fluidmaster parts

On a toilet that old I would recommend that you change the flush valve and float assembly to a newer version. One I particullarly like is the 400A Fluidmaster.It is simply to install and incorporates the flush valve and float valve into one unit.
They are simple to install as long as you can shut the water supply off. The instructions are printed on the inside of the box so just follow them closely. The only thing I add to there instructions is to use a small amount of silicone caulk around both sides of rubber washer that goes on the base of the valve.Adjust height on valve before you install it to get it close. The final float level can be set with spring clip on float rod.
I have been useing these valves for many years and they will work on most toilets and they are almost maintainance free.Added plus they are inexpensive. Thank you.

I would ckeck to see where water fill line is inside toilet tank and then adjust flush valve to try to get it to shut off at this point. Not knowing whether your toilet still has original flush valve it is hard to tell you how to fix it. If it has float mounted on rod to flush valve there is usually a set screw on the top of the flush valve in the center. Turn this screw clockwise to make valve shut off sooner. Try to set it so that water shuts off when it is at fill mark. If float is mounted on brass float rod you can support rod closest to flush valve with left hand and carefully bend rod down a little with your right. This will cause flush valve to shut off sooner. If the seat is worn to badly in flush valve you will need to replace it.

First thing to do is figure out if the problem is with the fluidmaster or with the shutoff valve. If the water doesn't run at all after flushing, then instead of cycling the shutoff valve, just loosen the nut where the supply tube attaches to the fluidmaster (under the tank). If the problem is in the fluidmaster, it will start to squirt out at you, otherwise it won't. Then you know what to disassemble and attempt to repair, or replace.

Replace the flappers, and clean around the flapper seat.

Make sure the water level is 1/2 " below the large vertical tube by either bending the float rod down or adjust the skinny silver rod on a Fluidmaster unit.