Land Rover Repair: transfercase, diff lock, linkage

Question
I recently purchased a 96 discovery.  The vehicle does not look like it has ever been offroad.  I tried to put it in low range and diff lock but it will not go.  The shifter seems like it is in neutral but it is still able to drive.  I talked to the dealer about this and he said it is a common problem if the vehicle was rarely put in low range and to spray a lubricant on the linkage and it should free it up. I have done this several times with no luck.  Is it possible I need a new linkage because someone tried to get it in low range before and bent the linkage because it was froze up?  Thank you.

Answer
First it must be in neutral,then you can move it into locking diff.which is to the left.if not you can have some one spray the linkage and keep doing it for a week or 2 then try again.My favorite in rust sprays are PB Blaster rust penatrant.good luck.