Hi Sonya,
Welcome! Are you doing a wheat-free diet or a gluten-free diet? Do you have celiac disease, a wheat allergy, or another kind of gluten intolerance? The reason I ask is that the precautions you need to take my vary accordingly.
Having never used a grain mill I'm not sure how easy they are to clean. I would advise disassembling it if possible to clean out all the different parts with soap and water. Soak it for a bit if you can. If you can't do that, and think there are places within the mechanism where flour might be stuck, I would sell it on EBay and buy a new one. It's just not worth getting sick because of gluten residue that you can't remove. Maybe someone here who has a grain mill will have more ideas for you.
Regarding breadboards - I would personally get rid of any porous bread boards, that includes wood and any plastic breadboard that has knife-marks in it, which are great places for gluten to hang out. This would be a good time to invest in either non-porous breadboards (such as glass) or new wooden or plastic ones. I don't know of any way to remove all gluten from a wooden breadboard, seeing as wood is absorbent and no amount of soap and hot water can "kill" the gluten. The same thing goes for non-stick pans and cast iron pans - Generally speaking, there are too many nooks and crannies (obvious for cast iron, but non-stick's nooks and crannies come from the surface getting scraped by utensils) to clean out fully. But everyone has to weight their own risks and benefits. I have kept my cast iron pans and just scrubbed and reseasoned them several times - And I have kept some of my higher quality non-stick stuff that didn't have any scratches in the non-stick surface. No problems so far. Everyone approaches this stuff differently.
Another thing to be really careful of is the toaster - Toasters are great ways to get glutened, as crumbs can hang on to the surfaces.
Anyway, it's your call, but I would personally recommend scrubbing and reseasoning cast iron at the very least - Or replacing the griddle if you're very sensitive to gluten and/or there are any nooks and crannies or other places gluten could hide out on its surface.
Welcome, and good luck!
Isaiah
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Gluten-Free By The Bay
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