Dual button WC Cistern assembly instructions?

Hi We have a dual push button WC Cistern. After button was pushed too vigorously, the Cistern kept filling and would not stop. On removing the cover, I found that the water level was not rising so it is just draining out. It seems the float valve chamber has got detached from the central siphon assembly. (When I manually lift this I can stop the water running). I need to find a way to reassemble this linkage. It seems to have a serated screw which I beleive would interconnect with the serated screw within the Siphon assembly. I will be very grateful if anyone can point me to an online drawing or similar information which will help me to see how to do this.