Cistern Fluidmaster PRO550UK push button does not stop water flowing after flush

[kez1]

I have the Fluidmaster PRO550UK fitted to a cistern in the house.

https://www.amazon.co.uk/Fluidmaste...ncoding=UTF8&refRID=X9T0EAWVS9C7588BV1R7&th=1

Generally it works exceptionally well, but occasionally when the large button is pushed all the way down - for the full flush - the seal is not re-made when the button is released and water flows continuously into the pan.

(When only the partial flush button is used there is enough weight of water to re-seal the cistern when the button is released, and everything works Ok).

When this happened before I fiddled with it, cleaned the black rubber seal at the base, and other seals, then re-fitted it, and the problem went away. This time I have done the same with no success.

There is nothing loose and nothing appears to be broken.

Anyone any idea exactly what might need adjusting here / what the issue is here?

Thanks

 

[terryplumb]

Fit a new flush valve as yours is sticking ,maybe cable mechanism. You can buy a new valve and just fit the top half to the existing base.