How do I adjust this?

[diy_fun_uk]

Or indeed is there any adjustment?

Background. It's a fire door so I don't want to do anything that compromises that. The issue is when the door is closed and locked, it's possible to push/pull the door slightly against the gasket.

Normally in this scenario, I would adjust the hook keeps to draw the door in more when handle pulled up and hooks engaged. However how is this achieved with this style? Is it something to do with the two square lugs? Do these get pressed in to adjust the keep left/right as required? And if yes, do I need to loosen the inner most screws first, adjust lugs and then retighten the screws?

 

[crank39]

Loosen the 2 innermost screws, only a full turn needed and they're only tiny, then slide the box hook box sideways for more or less compression