Somebody suggested rubbing down the interior with alcohol. He had experimented and concluded that the yucky plastic residue is soluble in vodka. First, I removed the tube that carries the hot water/steam and ran it through the dishwasher. Then, I wiped down the interior with about a shot of vodka on a paper towel.
https://www.amazon.com/Mr-Coffee-12-Cup-Programmable-Thermal/dp/B0047Y0UQO

