I am not sure what mark you are referring about? The smeared spot where I finger swiped? I have never seen belt dust but this is definitely oily grease build-up. Probably end up yanking the head unit off.Whats that mark on the head unit,to the right of your finger?Almost right inbetween the bracket and head unit.
I havent gone thru the box, is the card in one of the bags with the instructions or something?Bought it through Beefcake last April...dumb me didn't send in warranty card.