Hard drives that have expired on me historically have warned me in some fashion, often by emitting strange noises from the spinning parts. This one didn’t - unless it did it quietly and it was masked by the fan noise.
Of course a contributing factor is that the machine is on 24/7 since it is the gateway (not A Gateway though) machine for the network. Except for periodic reboots and openings for vacuuming it has been on continuously since I built it whenever that was - long enough for the CMOS battery to die. I had to put a new battery in it before it would tell me ‘NTLDR missing’..
It’s at least four years ago, I could tell you if I could get on the machine.. ;-)