Owning both a Westy and a GL...

That duct is to provide fresh air to the (non-existant on the Westy)
overhead vents. It's "plugged" because the overhead vents ain't there
on the Westy.

To tighten that plate, you need to remove the surround that the door
attaches to.  It's held on by a couple three screws under plastic caps
on the front. (IIRC. It was a few months ago when I pulled it apart to
tighten up the hinges and latch.)

Jim