A probe assembly can be connected and disconnected from its electrical harness within a vacuum chamber so that the probe assembly with the work piece mounted can be rotated and tilted without interference from a cable, and can then be reconnected without opening the vacuum chamber. Also described is a means of grounding a sample and probes when the probe assembly is disconnected from its electrical harness and a means of preventing damage to the probe mechanism and the probe itself by ensuring that the probes are not sticking up too far during operations.