Both the old and new adjustment screws have a recessed area behind the screw head. The HL assemble has to ears to accommodate the head.
Question is: How do I get the recessed portion betwee the ears ? On my pass side, I left the recessed part outside ears.
Top pic is the original screw; bottom pic is where I ended up...
@Mikey914

I replaced my headlights from Sealed Beam to H4 units last week, so I did have to take that apart. I could 'click' them in with a little force.

Thanks. I’ll click them into place.

Sorry late to party,
Yes should pop in.

OK - should it be "popped in" before threading into the new block ?

Yes.
The block slides into a receiver to hold it in place. The screws are best replaced in the ring while off. Not to say you can't, I just have done them in sets.