Push Button Toilet Flush That Keeps Dripping Issue

[Wilsonj1]

I have read a few comments and questions before about push button flushes that continue to drip / run.
In our case if you push the flush it runs as you would expect but a fairly large amount of water continues. If you push the button again in the right way it seems to click and then the water completely stops, filling the cistern and returning it to normal.
Does anyone have a suggestion on how to fix this?

thanks

[lets have a look]

You need a new syphon,post a pic and i'll see if i recognise it