Not sure this can help but I have the older type of Cassette with 12volt flush. It has a large knob to the left [facing toilet] and a toilet roll holder to the right sunk in to the flush water tank.
Mine did the opposit by jamming shut so I put a belt around the knob and pulled gently on the belt strap tightening its grip on the knob and gently added more pressure until the blade popped open. I gently closed it then slid the tank out and opened the blade using the rectangular knob on top of the tank and coated the rubber seal slot where the blade goes with olive oil, obviously wearing rubber gloves.
Go easy with it or you might break the operating rod.
Look at the holding tank through the outside door and see if there is something obstructing closure first.
Rob, March 2008
