I believe I have the same problem as you. DbPower sent me a replacement unit which is now displaying the same symptoms after several months of use. The noise is the fan squealing due to lack of lubrication at the bearings. The brown smudge is a result of improper cooling and overheating of the LED light circuit as a result of the defective fan (my second unit did the same thing because cooling is insufficient overall). Without taking it apart, I can only assume that it is the LED itself or a plastic lens or filter within the lighting circuit.