There's a reason they tell people to never wash their car with dishwashing soap, and it is because those soaps will strip away whatever wax you had on there. So I'd get a bottle of Dawn, Joy, Palmolive, or whatever other dishwashing liquid, mix a little of it into a bucket with some water, and try washing the cladding to see if that takes it off. But now you'll want to be careful to keep the soapy water off the paint/wax. :-)