Hellobee Boards

Is it a front loader? Is there mold in between the seal and the metal spinner thing? You might clean out the drain plug and filter, there might be a blockage there. I found this video on Youtube that I thought was helpful, I'm going to do this on my washer soon.

We actually got rid of our front loading HE washer because of this and went back to a basic top loading washing machine. It didn't matter how many cleaning cycles I ran or what I scrubbed the rubber seal with(it holds water and gets moldy), our clothes stank. We are much happier with our top loader now and no more stinky clothes!

@littlejoy: Have you thought about changing up your laundry detergent?

Definitely check out the rubber ring/gasket for gunk. Sometimes even a sock can get stuck in that and you may not know it.
When this happens to me, I know it's time to run the Tide HE Washing Machine cleaner. I get them on Amazon and they knock any smells out for a good 2-3 months. You run it on an empty load hottest cycle. I think it dissolves any buildup and leaves it smelling great. BUT it's a strong smell. It's a good clean smell but it will fill your house, last for a week, and overpower your regular detergent when you wash your clothes for a week or so. It is a very nice smell but if you use unscented detergent I thought you should know.
May also be a way to use vinegar and baking soda (separately). I do that with stinky towels but have never done it on an empty washer.

I'd do a few things. I'd run either afresh or the ride washing machine cleaner. Id give all the seals a really good bleach wipe down and make sure the filters are empty
I'd run a few loads on hot.
Always leave the lid up especially since it's in the basement
I'd also try to change up your detergent game, if even for a short term. The more natural detergents can leave residue (and also they just don't clean as well no matter their claims). We have realllly been loving Persil recently.

I would definitely give the machine a good all over cleaning first (gaskets, drain/filter etc) and then run a machine cleaner tablet. After that then make sure you always leave the lid open!