When you burned up the other drive belt, you forgot to sand off the black carbon buildup that was left behind on the motor drive pulley. Lean the machine back and use some Emery cloth to sand the large groove of the drive pulley until all blackness has been erased. The noise will not be there again as long as you sand it down good. In rare cases, the pulley has been irreversibly damaged by heat buildup previously and the pulley should be changed. A simple Allen screw holds it on the shaft.