The checkout ui action is missing from quite a few kb articles on all our instances (dev/test/qa/prod). User wants to edit the article, but there's no checkout option therefor it can't be updated. We have a workaround, but that is time consuming and also not a solution.
I think you can accomplish the same thing by exporting the affected articles to XML, altering the <workflow_state> value from "retired" to "outdated", saving the changes, and importing the XML file.
