Over the past few days I've discovered that any white clothes that are washed in my Whirlpool Duet front loader washing machine are coming out with a polka dot pattern that looks very much like the pattern of the drum.

I've run my hand over the drum and I don't feel any residue on the drum.

I've cleaned out the filter and did find a sock that was shredded, but subsequent cycles of washes hasn't turned up any further clothes in the filter.

Whirlpool is no help. They only suggest I call a serviceman, and we all know that cost might exceed the cost of a new washing machine.

Any help would be greatly appreciated.