On certain vehicles, there is a sharp edged scratch on the open stay, which supports the tailgate when it is open, and it can damage the rubber seal for the gas cylinder inside the open stay when opening/closing the tailgate. The cylinder gas can gradually escape through the damaged seal, causing the open stay to lose its retaining power. If the tailgate is electrically opened under these conditions, there will be no fail-safe function in case of malfunction of the tailgate control unit, so there is a risk that the tailgate falls down.
