I had the same problem a few days ago. I used the cleaning attachment for at least 5 minutes (and still rubbish was coming out). I then put the iron in the sink and carried on cleaning - water and rubbish ran out of the sole plate. When it ran clear I stopped, plugged it back in and set the iron to low temperature, and set the steam to a low setting. That way some hot water as well as steam comes out of the sole plate (and more brown stuff!). Eventually the blockage cleared and the steam trigger started working again. Worth a try!
Ken, January 2009