Having the bottles topple inside the hood is very rare especially when correct mid section type & size is used & proper height is set up. More often the bottles topple in front of the entrance to the hood caused by mis-alignment of the bottles. Alignment of the bottle going into the hood is very important to avoid the bottle from topple or falling. You can attached a guide rod on your conveyor to make sure that each bottle is aligned in a straight single file before the bottle reach the entrance of the hood.