Apple announced late last week that they'll be expanding their iMac 1TB Seagate Hard Drive Replacement Program, which would increase the number of machines eligible under the program to include iMacs sold between October of 2009, and July of 2011 with 1TB Seagate HDDs:
Apple has determined that certain Seagate 1TB hard drives used in 21.5-inch and 27-inch iMac systems may fail. These systems were sold between October 2009 and July 2011.
Apple or an Apple Authorized Service Provider (AASP) will replace affected hard drives free of charge.
The Cupertino-based company launched the program back in July 2011, but at the time it only covered certain machines covered between May 2011 and July 2011. Apple have demanded that the program be extended, and pushed further back to previous-dated iMacs, including machines as old as those sold back in October 2009.