Sorted! - I was trying to integrate the adapter into the existing setup.
You have to remove everything from inside the clear oblong plastic box. (Is it called a boro?) All the coil and chimney stuff, not o rings or seals.
You then put the adapter on top of a nautilus coil and insert it into the box so that the adapter becomes the chimney.
Put the bottom plastic bit back on the bottom and make sure the seal is tight.
Put the black airflow wheel back on (it actually does something with a normal coil in).
Should end up looking like this:
View attachment 273477
I was trying to cram the adapter through the bottom hole .... sounds a bit rude