I think I might have a hard drive failing and I would like to get some secondary advice. Symptom 1: I am trying to move a large iPhoto library (475 GB) from my iMac with a 3 TB Fusion Drive to a 1 TB external Firewire HD. When the transfer starts, the projected time is about 25 minutes. At about 1.56 GB transferred, the speed drops dramatically and the expected time increases exponentially from there. I have not let the transfer more than a couple of hours and this trend never seems to improve. Symptom 2: Time Machine backups are failing at times, lately is more often than not. I thought this might be something to do with 10.10.3, but now I am less sure. Symptom 3: This Mac has often had some sluggish/unresponsive episodes where it required a reboot or a hard shut off. There were intermittent beach balls of death while the iPhoto transfer was underway. Things I have tried/looked at so far: I recently got TechTool Pro 8 and ran the test suite. It reports SMART and file structure as being okay, but a surface scan shows 80 bad blocks out of 5 billion on the 3 TB internal hard drive. TTP also did not report any files residing on these blocks. The internal SSD part of the Fusion Drive checked out fine. The external drive passed a surface scan and is a freshly formatted drive. I installed an eDrive on the Firewire HD and booted from there and attempted the same iPhoto library copy with the same results. It has been a month or two, but I have run things like Cocktail in the past to try and help with the computers performance with some small improvement. Are there any other recommendations for what to check next? The computer is: iMac (27", Late 2012), 3.4 GHz i7, 24 GB RAM, 3 TB Fusion Drive Thank you in advance!