Abstract: A sensor assembly on a crane apparatus includes a multi-pole switch such as a wobble switch mounted adjacent the head of a crane boom. The switch is carried by a pendulum arm and is activated by an actuating member engageable by the crane lift cable whenever the cable is out of plumb. Activation of any one of the switch contacts completes a specific circuit to illuminate a particular signal element in the crane cab thereby advising the operator in which of four directions the lift cable is out of plumb so the crane may be manipulated to obtain a plumb relationship prior to lifting of a load.