p38 2.5 diesel manual no low range

just wondering if it was unwise to leave the low range not working,will it have any long term effects on the box,as i have so far not needed to use it,it did not work when i bought it.
and is it hard to fix,is it a gearbox off to put it right or can it be done in situ?
your help on this is greatly appreciated.
also the switch does not light up,so no power getting to switch,fuses are all ok.

usually motor on t.box or ecu under passenger seat, wont hurt box at all as everthing in t/box still turns whatever bhi/low selected