We had a very bad smell from our W/mc - it was drain related - go outside the house and look for a drain inspection pit - lift the cover and look inside.
The machine drains into a a vertical pipe that seems to have no water trap in it and this allowed the smell to come into the house and the washer. I think there are regulations about the drain hose - having to be higher than the centre of the drum - to prevent siphoning back into the machine.
I tend to run my machine on the warmer programmes to kill-off any bugs in the pipes - some people use vinegar as a cleaning agent.
Follow your nose and get to the bottom of it.
Good luck...
Peccavi
May 2013
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