said by squircle:
The problem is the plastic itself has degraded to a point where it no longer stays inside the metal housing, so we'd need a complete replacement (even if it was just something we could put inside the housing).
You could get a reasonable replica of the whole aerator or just the plastic part made. You could ask this person for advice because he mentioned making a better version than someone else in some 3D printer site. »www.thingiverse.com/Kulitorum/designs