Remove the front cover by taking out the hex-head screws. With the front cover off you'll see a pipe which runs from the vent to where the detergent dispenser is (the bit where you put the tabs or powder in). This pipe just pulls off. Give it a good clean by running hot water through it and flexing it - you'll see all the gunge come out. Re-fit and screw it all back together. Hope this helps.
Jez, September 2009