Abstract: A method of testing an integrated circuit of a device is described. Air is allowed through a fluid line to modify a size of a volume defined between the first and second components of an actuator to move a contactor support structure relative to the apparatus and urge terminals on the contactor support structure against contacts on the device. Air is automatically released from the fluid line through a pressure relief valve when a pressure of the air in the fluid line reaches a predetermined value. The holder is moved relative to the apparatus frame to disengage the terminals from the contacts while maintaining the first and second components of the actuator in a substantially stationary relationship with one another. A connecting arrangement is provided including first and second connecting pieces with complementary interengaging formations that restricts movement of the contactor substrate relative to the distribution board substrate in a tangential direction.