Transfer case grinding wont go foward back just not engaging

You have trashed your transer case probably low oil or wrong type of oil no frils just replace the t\c with a rebuild or j\yard part its important that you get the numbets off the outside casting this is a relatively simple fix for anyone with any type of mechanical aptitude though i stress the importance of numbers once you have em get on the computer and find your part even check alibaba again this is a simple R&R