iMac Music help needed.

[upsidedown]

I used to keep all of my iTunes - or what Apple now so cleverly calls Music - on an external drive. A couple years back, I bought a new to me iMac with a lot more storage and imported all my songs on to it. Now, every 10 songs or so, this message appears; “The song “Surfing a Slow Wave” could not be used because the original file could not be found.” It’s not just that particular song, but whichever one “Music” can’t locate.

The issue seems to be that my collection of songs are only *mostly* contained in the same location, while others are scattered about in obscure recesses, sometimes within redundant folders; “/Users/stevemac/Music/Music/Media.localized/Music/Unknown Artist/Unknown Album”

Can anyone suggest a method to corral my strays - all at once?