You will need to take it apart and remove the drum to isolate this noise. One possible source is the drum baffles one or more which have something inside . It always amazes me of the coins and other items that get inside these baffles. If the rollers were replaced were the support shafts worn badly for the rollers.? Also check the drum in the area where the rollers run to see if there is a bump in the surface. It usually causes a rumble noise. Recheck the idler pulley shaft for a problem also.