i have a 1988 defender 90, and the diff lock wont engage, i have checked the linkage arm and thats all fine, so i cant think of wat it can be, the short lever goes into low range fine and goes back into high range fine, but it just wiggles side to side with no resistance. any coments will be greatly accepted, rele need to get it sorted as im off roadin it on sunday. cheers. dave