People say it can come from bugs in the machine because of constant cooler washes - they say (I have never done it) run the machine empty on the hottest wash cycle with a cup of vinegar in it - to kill off the accumulated bugs.
When we had a smell in our machine it was coming from foul water in a blocked drain. Sniff the pipe that runs off to the drainage system to be sure.
Good luck...
Peccavi, September 2010
