If you are using a Probe, connected to your device via a 6-Pin Lumberg connector and the Probe appears to be stuck in the connector, then it may have been over-tightened.
You should initially try to release the screw thread connector gently.
To prevent the connector from locking in the future, you could use food safe grease on the connector threads. This problem may also be prevented by keeping the instrument clean when in use.
If this does not work, you will need to return your instrument for service.