Try Smelly Washer. It's an eco friendly product that takes bad odors out of your washing machine. Smellywasher.com
I took one of those "Mr. Clean Magic Erasers" inside of mine and it just took the smell right away. it was awesome =]
There's a product called Smelly Washer that should do the trick. It takes out the smell washing machines start to get after a lot of use.
OK, so I'm 1/2 way there. So far, I've used these different products with the following results: Bleach
I would recommend starting an empty wash load and dumping a box of baking soda in; then stop the cycle and let it sit for 10 minutes. Then finish the cycle. If that doesn't eliminate the odor, try...