A method, system, and computer program product for sensing the presence and/or misplacement of mechanical sub assemblies (MSAs) within storage slots of automated storage libraries. Each MSA is tracked based on signed empty cell barcode labels. Signed empty cell barcode labels are utilized to uniquely identify the frame, column, and row coordinates of one or more MSAs. The storage library automatically scans all signed empty cell barcode labels utilizing a scanner mounted on a robotic device. The system provides a counter for each MSA, allowing the storage library to track the usage of the MSA. As usage of the MSA reaches a predefined lifecycle, the library automatically generates an alert to replace the MSA. When a MSA is rearranged within the storage library, the library automatically maps the new frame, column, and row coordinates of the MSA. The counter dynamically modifies the usage count of the MSA according to the unique cell barcode label, thereby tracking all current and previous cartridges, and/or other items that may be scanned during MSA activity.