several things come to mind that you could try.....
but mostly you need a mold/mildew cleaner.....like a bathroom cleaner, especially with bleach.....
some of these cleaners have a 'deep root' cleaner to sink way down into the rubber to get rid of mold.....
one treatment may not work, you may have to spray and let it set, or even taking a toothbrush for a little scrubbing on tough areas...
I have the Frigidaire sister to your set.....so theres not really a clean washer cycle, granted not really needed.....but if you must, a long hot wash cycle, and using dishwasher detergent or chlorine for a pool will clean your unit very well.....once done, not a reason to ever have to do it again....
even after your all done, the mold/mildew will be gone, but it may have darkened the rubber some, but doesn't seem to be of any harm from there on.....hot/warm washes, and the weekly use of bleach in a load will keep it clean from there on out.....some mention of keeping the door ajar or leaving the dispenser drawer open.....I never do, and never have an issue....
not that COLD washes can't be used, but it should not be used as the only temp for every load......like I said, wash a few loads in mixed temps, and a bleach wash here and there will be all the up keep you will ever need...
hope this helps
good luck and keep us posted....