Fixing the DAL inlet valve on an Eljer Canterbury toilet?

The inlet valve on my center push button toilet does not shut the water off, The styrofoam float rises with the water and the little arm with a small rubber piece makes contact with tiny opening in the valve. There is a rubber membrane at the top of the valve.There is also a diverter channel at the top which sends some of the water to the tank and some to the hose emptying into the bowl. When the arm makes contact with the red piece sticking out of the valve the water does not shut off but squirts all over the place. In addition no water gets diverted into the hose. I replaced the membrane once but I have stupidly forgotten where I procured it. Is there any place in the U.S that handles these old DAL (Grohe) parts? Thank you all for any help or advice,
I am lost.I also have trouble with the discharge valve but I think your discussions will help me solve the problem if I can get the parts. I don't think trying to get them from England will be economically Feasible.

Thanks again.