In a device for ejecting droplets of an electrically conductive fluid, a vapor suppressing device is provided to suppress vapor of the electrically conductive fluid. The electrostatic chuck may attract a substrate during a substrate assembling process for manufacturing a flat display panel. A percentage of successful service interactions is determined as a function of concept node and, if the percentage of successful service interactions at the first concept node is below a predefined threshold, a content hole is flagged. On the other hand, no related image data is stored, the acquired image data is written to the storage device.