Yes, a long soak. Water is a powerful solvent.

I know some people don't like the idea of having something in their sink for 2 or 3 days, but it really is the best way to release almost any cooked-on/burnt-on substance...

..........and if after washing/soaking your insert any food debris still remains, a little Bar Keepers Friend with a scrub brush will magically remove what remains. BKF will not harm the glazing on the insert.

Dan

Thanks for the suggestions. I soaked and then used BKF and there are still little white flecks. I am getting rid of this one as it's not worth the trouble. Another so-called improvement. My old Rival with the non-removable crock was a breeze to clean.

I use a Dobie pad with the Barkeepers.
What I wonder is does the light color really clean up better or does the food just show up more on the dark?
Kay

After doing the soaking & BKF cleaning procedures, there is no way those remaining little white flecks are food debris. Crock-pots do not get hot enough to really bake-on any debris that BKF won't remove. If what you see in the insert after cleaning is the size of specs......I would think it is a defect or part of the ceramic. If it is spotty, it might be soap residue that forms on drying.

I would try cleaning with Windex window cleaner and towel drying. If the spots are removed......it is just soap residue. If the specs remain....it is a minor harmless defect in the ceramic insert.

Dan