There's two bits to the blade movement, the drop and the swing, the drop being achieved by a two levels on the plate that moves with a slope between the two. It seems you need to disassemble the waste container.
The document linked in Sproket's posting is correct but you will have one hell of a job to twist the top plate using the cover as a level. Better to remove the cover (slide it out) and use a bit of 3x2 timber. You only need to turn it for the arrow to point from one marker to the other.
Having said all that are you sure you are fully moving the operating level on the toilet? They sometimes stick part open. Also remember the trap needs to be fully closed before the empty waste container is replaced in the housing.
If you do disassemble the waste container it is a good idea to have a new trap seal to fit, and make sure the float that triggers the full warning is sitting properly in its mount. If/when you fit a new seal wipe it over liberally with olive oil to help it work. It is also not a bad idea to put the full contents of a bottle of Milton in the container in nearly hot water and leave it overnight to remove the crud, especially the calcium from the water.
Good idea to use vinyl or nitrile gloves when working on the box.