Reminds me of an old hwops story where one machine just constantly failed despite replacing every part on the tray multiple times. The conclusion was that the tray was bad.

Google's definition of a server was (and still is afaik) based on the tray (chassis) so there was no way to replace it. IIRC it was "retired" with vengeance leaving a gap in the cabinet — a warning to other trays to behave.