Good day all. Customer's TA 356ci is making a grating noise. When i run Maintenance Mode U30 the noise is emanating from the feed drive unit. Feed drive drive unit and toner supply assy were replaced but noise is still happening. When I activate the other motors in MM no noise is heard. Noticed the feed drive unit is connected to a gear on the main drive unit. Could the main drive unit be the issue? Any other suggestions?