the frequency generator 76 also permits the gripper to lift and release the valve 18 if the valve 18 hangs up on the edge of the bore the valve 18 may hang up when it is initially lowered into nominal position and pulled off the robot 66 by the vacuum in the bore the valve 18 is lifted by the vacuum generated in response to the perturbation signal and the valve 18 is permitted to drop and be inserted into the bore using the vacuum as described above a preferred installation sequence includes picking up the valve 18 using the robotic gripper 38 the robot positions the valve 18 at a nominal position over the valve bore the robot head 66 is lowered until the main vacuum forces exceed the force holding the valve 18 to the gripper 38 and the valve 18 is pulled from the gripper 38 if when dropped the valve 18 enters the bore the process is complete if the valve 18 did not completely enter the bore the perturbation signal is started and the robotic head 66 begins a search pattern to find the bore centerline as described above because the perturbation signal may cause the valve 18 to be released from the gripper 38 without the necessity of overcoming the gripper vacuum force the clearance between the valve 18 and the robotic head 66 may be reduced in an.