https://www.hometalk.com/1254986/how-to-clean-a-front-loader-washer?r=2

After it is clean, make sure that you leave the door open between uses. Mine, that I got second-hand, has stains on the door gasket. Although it is clean, removal of the stain will require replacement of the gasket. Since it functions properly and I seldom use it as a showpiece, the staining is okay with me.

If its the gasket, I wipe with one of those cleaning solution wet wipes, and then use some vinegar. Don't close the door all the way after running washer, stick your box of dryer sheets in it to allow to dry.

That's the only thing, the front loaders get to have is mildew. Run the machine with 3 cups of vinegar and always leave the door ajar to get some air to dry it out.

Wash the gasket with bleach water and follow with straight vinegar to kill the spores. Make sure that you get in in all the crevices of the gasket, as it likes to hide in those areas. Leaving the door open will allow the inner basket to dry and also the gasket.

I would do a vinegar wash once in a while to keep mildew at bay...I thought about buying one to save on detergent for the environment until I've heard of this issue...

Try wiping with straight 91% rubbing alcohol. Should not only remove but disinfect.