HD cable + drive replacement
I've previously had Apple repair the cable while it was under warranty and that cable subsequently went out about a year after that. I was able to scavenge a HD cable from another MacBook Pro (mid 2011) and while not ideal, it worked well enough. Now I had the money and time to double down on the cable and leap the HDD space.
The repair went great. I was able to install macOS on the new drive prior to opening the case and test it via a USB3 HD sled I have, though the one from iFixit would have worked as well. After opening the cases and removing the IR bracket from the proper cable the rest was a breeze. The instructions were easy to follow and gave me confidence when I had a question.
If you don't have a solid set of tools for working on electronics, get one from here.