Hitachi 870 making noise in the pump drive area

Please help, we have a Hitachi 870 Digger making noise in the pump drive area. We cut open the big filters from the hydraulic tank and found small traces of metal. Management suggested to change all 4 hydraulic pumps. New pumps were fitted but the noise is still there slightly worse than what it was before the pumps change out.This machine has 12000 hrs and the pump drive has never been replaced or repaired. We are not sure if the pump drive might be causing this.

Hitachi 870 making noise in the pump drive area