EX120-3 Slew Gear Bearing Grease Dilution

My Ex120-3 Slew Gear Bearing grease is being diluted with hydraulic oil. If this is from the Swing Motor reduction gear, why isn't the level going down? The oil in the reduction gear appears to be hydraulic and not gear oil. If the Swing motor seal is leaking, wouldn't the reduction gear box be overflowing. I guess the swivel is ruled out because it's leakage would be internal. I have recently purchased this machine.
Mike

EX120-3 Slew Gear Bearing Grease Dilution