I went mudding, i got stuck. My 1990 Range Rover is AWD (permanently in 4-wheel drive) and i have the mud terrain tires. When I got stuck, not all of my wheels were spinning (only the back were). I have the differentials, AND LIMITED SLIP VISCOUS COUPLING (like lockers). Why is this happenning? Are they broken, is there a way to check if one of these is seized and if it is partially seized can i fix without replacing? I have a workshop manual. please help.

 

Were you in 4-HI or 4-LOW when you were trying to get unstuck?
Did you try to shift from one to other while you were stuck?