Tony's instructions do work!
At the back of the machine remove 4 screws to take off the back panel at the bottom. Look inside with a torch, and you can see the bottom of the drum with the main black rubber drain coming out of it held on with a hose clip.
Loosen off the hose clip and the drain should just drop off the drum.
Inside the top of the drain there is a white plastic trap. This you need to remove and clean and then replace. I found it easiest to locate the drain against the bottom of the drum (because it will only fit a certain way) and then bring the black rubber drain and hose clip up to meet it.
Tighten the hose clip, replace the back panel and you are done. Altogether it took me about 35 minutes. (easiest £80 call out fee I've ever saved!)
Run a rinse to clean out the pipework, and away you go.
Remove the large hose clip and
Tad, November 2007