I have a newer (3 yrs old) front loader, and the directions specifically say to leave it open when not in use in order to avoid odor and wetness problems, but you should check the owner's manual that came with your machine. If you no longer have the owner's manual, you can easily find it on-line by googling it.
You leave it up at the end of the wash cycle. It will prevent the washer from having and odor. Down for the wash cycle
