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I had the same problem when I opened my egg last week. I filled up the Egg with lump, lit it and took the temp up to 600 degrees for one hour. Then shut it down. The mold is gone. I just ordered the new stainless steel vent cap that I can leave open without the rain coming in. I also just got a much needed new egg cover that is vented. So I hope it won' t happen again. It was sickening.