Recently updated the HDD to SSD. Do I need to update to a new cable?

Yes! You need a new HD SATA cable.

Here’s the needed part MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable and yes! This is the 2012 version of the cable which is better designed for SSD’s. Here’s the guide you’ll need to follow MacBook Pro (13 Zoll, Ende 2011, Unibody) Festplattenkabel austauschen.

You do want to place a strip of electricians tape on the uppercase where the cable crosses over as the rough aluminum wears the cable. In addition you need to be careful on the folds! Many people bend the cable across a sharp ruler which will damage it! You want a smooth arc with no sharp bends. I use a ballpoint pen ink tube to shape the radius of the folds.

Once you’ve fixed the hardware you really want to make a backup using TimeMachine and then reformat the drive and re-install the OS again. I strongly recommend you stick with Sierra!

High Sierra & Mojave will create issues with your system! Basically, these newer OS’s replace the HFS+ file system with APFS during the install or upgrade process. What makes sense for the newer PCIe/NVMe blade drives does not fly here with the older SATA drives. You want to stick with HFS+ and you can’t roll it back when you install these newer OS’s.