Hi

I've just installed a Grohe Adagio concealed WC cistern. I'm having
problem with the filling valve. Does anybody have any experience with
these?

Basically the valve doesn't close off when the cistern is full. I've
lowered the polystyrene ring on the valve right to the bottom of the
tube (equivalent to the ball on the lever of a normal cistern) but
there still isn't enough force on the lever arm to close off the valve
when the tank is full. I can nudge it shut with my finger but the water
just won't do it. Any ideas?

Thanks
Pete