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I see that they are nonremovable, which, unfortunately, is common for waffle makers, esp. older ones. I would suggest Formula D, or Dawn Power-Dissolver, if you can still find it (some places discontinued it). Or maybe oven cleaner. To prevent the oven cleaner from getting into the waffle maker, take a container of oven cleaner outside, and using gloves and safety glasses, spray some into a container of some sort - a jar or throw away plastic - and using a cheap paint brush, brush it on the waffle maker, keeping it wet for a half hour or so, then use a cheap toothbrush, and see if the cooked on gunk seems to come off. If some comes off, but not all, do another brushing of the cleaner. Once clean, wipe it off with paper towels, then wipe it clean with some vinegar, to neutralize the lye, then clean with some regular dawn, or whatever you use, then water. Hopefully, it will come off.