From your pictures there is nothing wrong with your heating element, you can test by opening the DW during heated dry and see if the element is getting hot by dripping water on it to see if it sizzles.

The spot in your picture is just mineral build-up flaking off, the DW was either used with cheap detergent, too little detergent, hard water, and or may not be getting enough water likley due to a bad inlet valve.

If you correct the problem that caused the mineral build-up it will gradually go away.

PS, I am more concerned about the little rust spots on the porcelain tank in your picture, KD-23 DWs have a lot of problems with the tubs rusting through, it is easier to fix before it rusts through completely.

John