It sounded like it was coming from the blower wheel area and I noticed some fine cracks on some of the blower wheel air foils. I replaced the blower wheel. I had to break apart the old blower wheel with a pair of pipe pliers in order to get to the molded-in threaded insert and remove the insert before installing the new blower wheel. So far the noises are gone after a few drying cycles. I also had to remove the blower housing in order to get an adjustable wrench on the shaft and vice grips on the threaded insert.