hi all, right, centre diff lock isnt working on my 300 tdi 90 i think??.. :-k ive removed the back prop to change a whining diff and thort id see if the diff lock was working by trying to move the vehicle and it duznt move. the light doesnt work either on the dash, what is the problem? new secondhand transer box? or is it an easy fix, everything else works fine with the truck though it has done 160000 miles. any advice be great, cheers.