Over the past several weeks, CBS News has spoken with roughly two dozen Department of Homeland Security personnel spanning career civil servants, uniformed personnel and frontline staff about the institutional strain caused by the partial government shutdown , now in its 68th day. Their roles differ, but the sentiment is strikingly consistent: They feel forgotten, not just by Congress, but by a political system that in their view, has little understanding of how DHS functions in the daily lives of Americans. This is what happens when one of the federal government's most sprawling and mission-critical agencies is told to stop working, to go without and to simply wait.  "What we do only becomes visible when something breaks," one employee said. "And right now, we've reached a breaking point." The paper clip economy Inside DHS headquarters, the shutdown has produced a kind of bureaucratic improvisation not seen in decades.…