It has been quite some time since you posted this question but I just stumbled upon it and thought I'd reply in case others read it. In my opinion your hard drive replacement may have actually been a level 2 repair. I don't know where the hard drive was situated in that particular Mac computer.
General definitions:
Level 1: Anything you can detach from the electronic device (laptop, phone, tablet, etc.) without taking it apart
Level 2: Swaping out internal parts without soldering the smart device/tablet/computer.
Level 3: Anything soldered to the mother board (circuit board or logic board are also terms used) that must be removed via heat exchange or soldering technique.
I hope this helps -- not sure if the original poster will ever see this!