Smelly washer works. It is a good product developed by a local appliance repair guy. Smelly Washer
However, even he said you do not need it. He had 3 tips.
1) Use powdered detergent not liquid
2) Use the reccomended amount of detergent. In this case more is bad.
3) Occasionally add a cup of baking soda to a load of laundry. The smell is from soap scum and the baking soda acts as an abrasive to remove the scum.
There was an article about him and his product in the StarTribune a couple years ago. We have followed his advice and it solved the problem.