My cistern doesn't seem to be filling up properly... when I try to flush, there doesn't seem to be enough water... I have to hold the float down for approx 15 - 20 seconds to enable more water to fill the cistern... at this point the toilet will flush.. any ideas??

The water in tank should be 1/2 inch below overflow tube. This should give u enough water to have a good flush.

To adjust float bend rod to float so that float is raised.See image on right.

For float on left, adjust water level link to raise float.

Chuck