In a quick-change system for exchangeable machine elements, particularly in a container processing machine in which the machine element (E) can be brought into a target position and can be localized in a target position by a securing unit comprising at least one securing element, at least a second securing unit (P2) is provided with which a machine element that either has not been brought into the target position or that has moved out of the target position (X) can be localized in a securing position. The securing position is detected and evaluated as grounds for a corrective action before commencing an operation or during the operating sequence before a corrective action is initiated and executed.