Grasp the short arms and press towards the short body.
With short arms fully pressed in, carefully slide probe tip through hole on top of short and straight down past the internal cams. Be careful not to bend the probe.
Make sure that the probe tip is inserted into the internal hole, touching conductive elastomer disc below.
Supporting the short from the bottom, slowly release the arms so that cam action presses probe tip into the conductive elastomer disc.
Once the short arms are released, steady the short so it does not move excessively. You can now completely let go of the short to make the calibration measurement.