Try using comet. Comet will help in dis glazing it. obviously if you put powder near a running belt you will get the same result as trying to pour oil into a running engine. The best option; safety! Turn the dang engine off, take some comet and put it in your hand, spit in your hand to make it not powdery anymore and rub it on the belt in a few places, both the under and top side, see if that helps. I did it to my truck tonight after reading some pieces about it.
belt noise, how do you eliminate it 1995 f150 - Ford Truck Enthusiasts Forums
Just my 2 cents. Hope my serp belt doesn't get too rugged and fall apart haha!