I have undone the repairs of the Dabus at one point in the alley of lingering sighs but at the other point it does not give me the option to undo the repairs when I examine the building. I cannot get past the face into the next area.

You need both the hammer and the crowbar to undo the repairs, you are probably missing one. The dead dabus has a hammer and there is a crowbar lying around somewhere.

Another spoiler if you missed the crowbar.
It's in the tenement of thugs.