Adding Hard Drive Bracket Retention Screws
30 - 45 minutes
I had upgraded the mechanical, platter-based drive in my MacBookPro to a SSD (Samsung) and failed to put the existing hard drive bracket retaining screws back in. Moreover, I lost the screws! I ordered new ones from iFixit.
Easy-peasy, just removed the drive, per iFixit's instructions, added the screws and voila!
Take your time, be patient.