The most common cause for the waste to get stuck in the closed position is lack of cleaning and as such the mechanism is clogged with gunk. This will require you to remove the cartridge and clean the mechanism. The best way to do this is get a piece of string or Dental floss and wrap around just under the edge of the button cap and pull straight up. This should remove the whole cartridge. Operate and clean the mechanism and the throat of the waste and reinsert cartridge. If mechanism no longer works, please contact us to request a free-of-charge replacement.