Diagnosis
Odors are trapped in the plastic, especially the Tritan copolyester used for the jar. Tiny food particles and oils embed in microscopic scratches.
How to Fix It
Fill the jar with warm water and add two tablespoons of baking soda. Let it soak overnight. Rinse. If that fails, use a vinegar solution: one part white vinegar to three parts water. Soak for several hours. Rinse thoroughly.
If That Didn't Work
For persistent odors, make a paste of baking soda and water. Scrub the entire interior, especially under the blade assembly threads. Use a soft bottle brush. Rinse with very hot water.
Heads Up
Never use bleach. It can degrade the plastic and make it more porous. Avoid abrasive scrubbers that create scratches where odors lodge. Always unscrew and fully clean the blade assembly separately after each use.