How to stop water leaking into the toilet bowl?

[Neo19]

Hi everyone,

I've noticed a leak in my toilet bowl, and now the tank isn't filling up.

I opened it up and saw a broken disk-shaped part (see photos). Any idea how to fix this or what part I need to replace?

[Neo19]

Thanks @EricL & @MitchellMc 

I've finally finished the job. The multigrip was godsend as I wouldn't have been able to remove the old valve without it. 

For the broken plastic clip, I've foun an exact replacement - https://www.bunnings.com.au/fix-a-loo-toilet-seat-blind-fixing-kit_p0018498

It was very easy to use this!

Everything is working now although there is only one concern remaining. The old flush outlet valve had an attachment at the top which had a clip sort of thing that used to keep the inlet valve mechanism in place.

The old mechanism doesn't fit the new valve. Now my water inlet valve is just propped on top of the new outlet valve mechanism, there is nothing to hold it in place. See attached photos. Eventually, at somepoint it might slip off without me knowing and the inlet water stopping mechanism might fail, I'm afraid. 

Any suggestions? 

Water inlet valve propped up aganist new flush valve ventOld flush valve with clip holding inletOld flush valve with clip holding inlet - top view

[MitchellMc]

I see the new valve has a fitting on the top of that vertical pipe where the fixing mechanism was positioned on the old valve, @Neo19. Can that be pulled off the pipe and the old clip mechanism be installed?

Mitchell

[Neo19]

Thanks @MitchellMc I've tried doing that. it was very tight and the old one has groves inside while the new one seems smooth.  What if I gently cut the fitting of the new vertical pipe with a stanley knife? Do you think it serves any critical function, just in case I'm unable to fit the old one then! 

[MitchellMc]

I believe the vertical pipe would be an overflow preventer @Neo19. If, for some reason, the inlet valve fails, the height of the water in the cistern is controlled by allowing it to run into the top of the pipe and then into the pan instead of overflowing out of the cistern. How close is the old fitting to being pushed onto the new upright pipe? Would sanding the grooves on the inside of it allow it to be pushed on? It would be good if we didn't have to modify the top of the new vertical pipe by cutting it.

Mitchell