Cistern fill valve replacement (won't stop filling!)

[sceptre0]

Hi all,
Our toilet cistern fill valve won't cut off when the level reaches where it should. I replaced the diaphragm a couple of months ago due to very slow filling and now this issue started today.

So, I guess there is something not right with the valve - is this a suitable replacement ?
https://www.screwfix.com/p/fluidmaster-bottom-entry-fill-valve/84007?_requestid=220029

My next challenge is the houses previous owners decided to box in the isolation valve just beneath the cistern so I have to try and remove some tiles to gain access!

Thanks.
Anthony

 

[sceptre0]

For reference, it's a SIAMP valve, at least 13 years old

 

[just pumps]

Yes the fluidmaster will do, others may tell you to get the one with the brass shank.

 

[sceptre0]

Yes the fluidmaster will do, others may tell you to get the one with the brass shank.

Thanks.
What would be the advantage of the brass shank ?

 

[just pumps]

Thanks.
What would be the advantage of the brass shank ?

Less likely to cross thread the nut when tightening. Thats all.