Sounds like your syphon (?) has had it - it's the bit in the cistern that is activated when you push the lever down. Lift the lid and have a look while you flush - you may see some thing that makes sense!
Richard
January 2009
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix toilets.