Whirring from Transfer Case

The Transfer case of my 2006 Nativa (Montero-Sport) generates a Whirring Sound when it is in 4WD at all speeds :uhoh: .

The Dealer awaits a Repair/Info from MMC-Japan before he can mess up the vehicle.

Would any of you know how to solve/stop this damn Whirring sound????

Thanks and have a good day.