What is the best way to clean the inside of your washing machine?

I have a top loading washing machine which is now about 10 years old. I have noticed darks seem to pick up fluff when they are washed. The metal bowl you put the washing in is fine, but I think the bowl THAT bowl sits in needs cleaning. I remember when I had a tradesman around, he said washing products leave a residue on that inner bowl. How do you give your washing machine a good clean to get rid of any washing product residue?