It's probably a bit late but this is probably because some small clothing item has moved into the outer drum and is now blocking the drain-exit from the outer drum.
You might try removing the large (4cm diameter) pipe from the bottom of the plastic outer drum (leading to the pump) and checking if you can fish it out. However, you'll probably find you have to place the machine on its side to do this and the item blocking the drain hole may thus fall back in when you tip it. So if possible try not to tip the machine over too much (and be gentle) when you do this.
It's actually very quick and easy.
Clint, December 2010
