WC constantly filling but not holding water

[bullethead123]

Hi all, I got a wc that is not holding water. All the water from the fill valve goes straight diwn the pan.
I took the gubbins (is it called a syphon?) out and maybe it is down to a seal not sealing (see pics below). The third pic shows a seal which perhaps should be attatched to something but isn't. I guess the best fix would be to get a new (syphon?). Can snyone point me in the right direction please?

 

[terryplumb]

Re fit the seal ,if that doesn't stop water running into the pan fit a complete new flush valve.

 

[bullethead123]

Thanks for your response Terry. I noticed that the seal is 'wedged' between 2 plastic disks held together by a springy plastic clip which isn't perhaps as springy as it should be. With minimum force the two discs seperate allowing movement of the seal. My solution was to use standard araldite to secure the clip and one disk together. Seems to work fine now.

 

[Scally-Ho]

If replacing the seal, always check the seating where the seal rests upon. Any hint of roughness, then replace the complete flush valve.
If I had my way, then syphons would still be fitted to cisterns. These flush valves are problematic by design.