Abstract: In a CATV terminal, in which it is desired to maintain privacy or security, the cover of the terminal must be removed in order to permit access to the terminal interior. In accordance with the invention, however, removal of at least one of the cover screws causes shifting of a spring loaded movable member that normally receives or is retained by the screw. The shifting movement operates a switch, causing transmission of a signal to the head end that indicates that an entry has been made to the terminal. In one form the movable member itself is threaded to receive the cover screw, and in another form the movable member is arranged to be initially aligned by limit stops, then released from the limit stops and preloaded against the restraint of the cover screw. In either form the mechanism can be arranged such that the screw cannot be reinserted to provide a positive indication of tampering. Also, a special device may be used by an authorized individual to reset the mechanism when appropriate provision is made.