Old HDD died. Looked like replacement was going to be an expensive out-of-warranty repair, but iFixit came to the rescue!
Piece of cake! The Heavy-Duty Suction Cups from iFixit got us past the display glass and into the system guts to do the HDD replacement ourselves.
So glad iFixit has the tools necessary to do on-site repairs without having to resort to an "Authorized Apple repair facility".