Diagnosis
Food and liquid get trapped in the silicone sealing ring (gasket) that sits between the blade assembly and the bottom of the pitcher, leading to mold and grime buildup.
How to Fix It
You have to remove the blade assembly. 1) Unscrew the large black plastic retainer ring at the bottom of the pitcher by turning it counter-clockwise. 2) Lift out the metal blade unit. 3) Underneath it, you'll find a thin, clear or white silicone ring. Pop it out carefully. 4) Wash the ring, the blade unit, and the pitcher base with hot, soapy water. A small brush (like an old toothbrush) is perfect for scrubbing the groove where the ring sits.
If That Didn't Work
For stubborn stains or mildew smell, soak the silicone ring in a solution of one part white vinegar to one part warm water for 30 minutes, then scrub and rinse thoroughly. Baking soda paste can also help scrub away stains.
Heads Up
Never put the blade assembly or silicone ring in the dishwasher. The high heat can warp the plastic and degrade the silicone. Always hand-wash these parts and make sure they are bone dry before reassembling to prevent new mold growth.