How about vinegar and baking soda.......you can always claim you are doing a "volcano" experiment...lol!

Try to cover the bottom with cooking salt, and put it out in the sun for a few days, usually works for burnt on gunk.

It sounds like all the possible solutions have been presented. I'm going to watch this thread to see what worked in the event I should have this problem in the future.

How about an oven cleaner gel. Haven't used it on a crock pot, but,I brush it on burnt oven walls and after a few hours everything wipes clean with no scrubing - why wouldn't this work with your crock pot???

Well, it's been a couple of weeks since you posted this thread for help with your crock pot. Have you tried any of the suggestions and did any of them work? Enquiring minds want to know.

If you still have not gotten it clean by now, try Easy Off oven cleaner. It works wonders. It works best if you heat the crock slightly (warm only), spray heavily and let it sit a few hours or overnight. The fumeless kind doesn't work as well, so becareful of the fumes. Use outside when possible. You may have to do it more than once.