When you have issues with sealing a tube in your tube filling machine, check these points as a start. 1: The ingoing materials: Ensure proper storage of tube boxes. Also, make sure that the acceptable tolerances are followed. 2: Size parts: Use only parts adapted for the size in use. Check if the tube is stable in the holder. It could also be too narrow. 3: Filling station. If the sealing is bad quality, the filling station needs to be checked. Do you have product splashes inside the tube? The settings might need adjustment.