I have a Used Ambex Y 5 that I am cleaning up. I have taken the perforated part of the cooler out. The holes are plugged with coffee pooh. I can get that out with any ice pick or something; the back side has coffee pooh on it to. Hot water and detergent does not seem to do much. It seems to be aluminum so I do not want to wash it in the dish washer or use oven cleaner. How do you, clean this thin…