I have a 1969 Series II A Rover that my husband always drove. My husband died in March and I am driving in snow. What is the sequence of engaging 4WD ( I forgot). I have ARB air locks switch with a compressor switch and the wheels have no levers to turn/lock. There is a round keyhole? on the wheel. Should I look for a round key to turn/lock the wheels or does the ARB switch with the compressor switch do that? Do I put main gear in neutral then push down on yellow knob then flip the switches? What is the sequence?