not sure if the trsansfer box is working or not i can move the lever over but no light on the dash. could i check its locking up by jacking up a front wheel with the hand brake on check it spins then move the lever and see if its locked, if the wheel does lock up is it just a case of a micro switch that gone if so where is it on the box

Yes, Andy that sounds right. The switch is on top of the transfer box and is a pain to reach from underneath. If the difflock is working it could be the bulb on the dash that has gone or a fault in the wiring. You can check this by disconnecting the two wires on the switch, short them together and turn the ignition on, the light should come on.