I just recently came into possession of a certain kind of Marx tin car from around 1950. I've determined that it has some sale value, but I don't know a damn thing about this area of collecting and need some experienced assistance. This car has sat in a basement for decades. It's in surprisingly good condition, but it's also accumulated a good bit of dirt over the years. Do the people that collect these kind of toys want them as they are, or should they be gently cleaned to remove surface buildup, or what? I want to sell this, but I want to make sure that I don't do anything to screw myself over and devalue the toy. Appreciate any help!