Toilet cistern playing up

[swampydrill]

I have an ideal standard Alto dual flush toilet. Once the toilet is flushed and the tank starts to fill up, there is a small amount of water going into the bowl, once the tank is full then the water starts flowing into the bowl more rapidly. I assumed there is a seal leaking on the dual flush mechanism but as soon as i turn off the water supply, the flow of water to the bowl stops and the level in the tank remains constant. Would this mean it is leaking on the fill up side ?, can't see anything

 

[footprints]

Most now overflow into the bowl, my guess is the filling valve or ballcock whichever you have needs adjusting or re-washering.