Jerry-
I think you misunderstood the problem I’m having. I haven’t lost the connection to the media, it’s just that FCP no longer recognizes that a clip in the timeline comes from a specific clip in the browser, even though the clip in the browser (which should in fact be the master clip for the corresponding excerpt in the timeline) does exist. I think in the Final Cut Pro lexicon, it no longer recognizes that the clip in the timeline is an affiliate of the clip in the browser.
Further complicating my ability to discern what’s happened, it turns out that not every clip in everyone one of my sequences has suffered this de-affiliation. Some sequences match back fine still.
Anyhow, if anyone has a way to “re-affiliate” in batches – hours of my life will be saved…