Cistern continuously filling

[AndyM]

Hi

I have a continuously filling cistern and i'm not familiar with the mechanism. 

its a dual button flush with a cable connection. 

water enters thru the grey cylinder. the red would normally shut the water off but lifting as far as it goes doesn't stop the flow or even slow it. 

how do i get the grey cylinder out without damaging it to inspect ?

it's not obvious exactly where water is entering via the grey cylinder any ideas on why the water won't cut off ? 

do you reckon replacement is needed ? it all seems a bit rickety