the transfer box out put brg stc1130 ,could be worn check it for movement shaft will move a bit as is a ball brg,garter spring often comes off during fitting if not held by vaseline or such,seal contact surface on flange often worn seal position can be moved so running on fresh surface or flange replaced,sometimes just poor replacement seal,breather on hi/low housing blocked,especially plastic extension pipe,where it runs up back of head