Land Rover Repair: diff lock wont engage, haynes repair manual, diy projects

Question
I have a 1997 Discovery LSE Automatic 4 liter.  I can not engage the diff lock.  I can get it into neutral but for the life of me can move it over to engage.  I'm not sure where I heard this but I've heard that this is a fairly standard occurance.  Is there a broken part or will simply taking it apart cleaning it and reassembling fix the issue?

Also do you recommend the shop manual?  Does it have detailed instructions?  I am fairly handy but would prefer to follow detailed instructions.

Thanks in advance.

John

Answer
Hi John,

consider changing the fluid in your gearbox.  I switched to synthetic and it seems to help.  I was told that it will help improve my gas mileage too.

If you are looking for a good Do It Yourself repair manual, I can't say enought about the Haynes Repair manual for the LandRover Discovery #3016.  Its only $30 or so and its worth it!  The LR service manuals are at least $100 and very good but I like the photos found in Haynes better than the sketches in the LR manuals.  

What Haynes does not cover, the LR manuals do BUT Haynes takes care of most DIY projects.  Something to consider.

Best of luck,

JohnMc