Uh oh - let's take care of that!
Here’s the remedy:
Leave the door open when you are NOT using the machine. This allows the drum to dry out. If the door is closed it seals the door and the inside stay wet and is a great environment for the mold to begin. If you’ve noticed a few spots of growth beginning clean the inside surfaces with a cleaner like Simple Green.
Just a note about high efficiency duos:
We put one in our home late last summer. Our biggest surprise at the time was the reduction in water usage (cut about a third of our water consumption) from the washer, but recently I noticed that over the last six months we’ve had a similar reduction in electricity use. We’ve done nothing different other than get the new washer/dryer. Wow!