I have had a Whirlpool Duet for about 6 years, too. I am going to get rid of it. It is so sensitive to sudsing. I use HE detergent and less than half of the recommended amount and I still get sudsing. Sometimes the water won't spin out of the fabrics and I'm left with a washer of soggy wet clothes that aren't properly rinsed. Yes I run the clean cycle regularly, no the hoses are not kinked and yes I wipe out the ring etc. Mildew has never been a problem.
My next machine is going to be a Speed Queen. I have one in the barn to wash towels for the cows--heavy duty use and gets the towels clean!