Kenmore washer dispenser problem

Our Kenmore front-loading washer (417.41142000 -- manufactured by Frigidaire, I think) no longer flushes the detergent and fabric softener completely from the dispenser. We've never used the bleach compartment, so I have no information on that.
It washes out most of the detergent (powder), but leaves behind a considerable amount of the liquid fabric softener. Even after a few cycles when no new fabric softener was added, some remains in the dispenser compartment.
The water supply is filtered, so the valves shouldn't be getting blocked with crud.
Any ideas?
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