Yes, there is a 'technique' to closing (and opening) the CF.
To close the camera, you:
1. Wind the rail back as far as it will go.
2. Unlock the front standard and push it back as far it will go - it butts up against a small section of rail in the back of the camera.
3. Push the front standard onto this section of rail and then lock it in place. (You should also remove any front shift/tilt you have applied, so that the front standard is in a neutral position.)
4. And this is the trick - move the rail forward about 1.5cm (1/2 inch) before you close the camera. If you don't move it forward, the rail gets in the way when you attempt to close the camera, and may damage something.
5. Finally, you move the rail forward as far as it will go - the rail meshes with something, locking the camera.
When you open the camera, you:
1. Wind the rail back a bit to unlock the camera.
2. Open the camera.
3. Wind the rail back as far as it will go, so that it butts up against the small section of rail.
4. Unlock the standard and move it onto the movable rail, and lock it.
These steps may seem complex at first but, after a bit of practice, it becomes automatic and only takes a few seconds. Quite a bit quicker than closing a 45A, especially if you leave the lens on the front standard.