This cable is fine. The problem is the cable directly at the LCD glass.
Yep, missing lines or columns is necessarily a problem between the LCD driver chip and the glass panel. If the lower ribbon cable was damaged, all characters on screen would have deformations.
I'd see if you can find a functional one with external damage or pen marked (unsurprisingly common with students). They go for not much cash and you can do a brain transplant fairly easily. Once the LCD goes on these they are nothing but trouble.
I buy and sell TI83/84s quite often. Its quite lucrative as there is a yearly cycle of sales and purchases as people leave and enter education respectively.
It's not that simple. There have been five or six different versions of the TI-83+, they all have minor variations on the display module. Some are 3.3V and other 5V. Some of them have the LCD controller circuitry on the main board and other have the same circuitry on the display module. There is a lot of info about that on datamath.org
I love using TI graphic calculators, I have several, but the quality of those LCD displays is just pure shit. They're selling them for around 100$, for a z80 CPU with an LCD, and still every new version does something to cut down the costs. The very first TI-83+ I owned as a kid developed the same problem where a line was missing. I tried heating the glass connection but looking very closely I found that the transparent ITO track on the glass for the missing line was simply cut just before arriving at the ribbon cable. I guess it was barely making contact, until one day it stopped conducting at all.
You could try to find a broken TI-83 and transplant the screen. But really it's not worth it. 90% of broken calculators you'll see will have LCD problems too. And even if you find one, you'll still have to pay something like 5 or 10$ for it. I don't know if it's the case everywhere, but here I can often buy used TI-83 for like 15 euros.