Hi could anyone help i've had my disco 200 for about 3 years now never had any problems with it untill today when i went to engage low box and it wouldn't go in i can get hi range in standard and diff lock but no low range in either standard or diff lock never had trouble with it before apart from it being a little stiff but i havn't used it for about 12 months normally use it about 4 times a year for shunting my caravan around and obviously winter but not used caravan this year untill now so could this be an easy fix i.e spray something with wd40 and work lose or is it a problem any advice would be gratefully received thank you