Update:
I checked the LCD panel connection to the mother board, and ensured that it was securely connected.
I also tried using a new custom resolution, 1920x1444 60hz, and to my surprise an image appeared on screen, but it was illegible and poor quality, same as the previous custom setting I tried. It's like the image is scaled to a lower resolution, and then scaled back up again to fit the screen.
However, 1920x1444 mode didn't appear vertically squashed like 1920x1080 did. When I played around with the scaling options, every scaling option kept the image at the full size of the screen. If you recall from my last message, in order to display 1920x1280 I had to play around with the Nvidia driver scaling options, otherwise it wouldn't cover the entire vertical screen with an image, appearing squashed.
Everywhere I can find specs on the VPCL2 screen say it's native resolution is 1080p, or 1920x1080. So I'm surprised 1920x1444 even presented an image, although a messed up image.
I may have found replacement parts on Ebay, by searching for "vpcl214fx lcd".which gives me an LCD panel by AUO, part number M240HW02. This panel is rated 1920x1080 60hz. So I was probably wrong about the 120hz frequency being native, which makes sense why only the custom resolution at 60hz kind of works.
I have a few theories about what's gone wrong here:
1) The panel is just ******, and needs to be replaced. Pure hardware issue.
2) When these problems first started, a bunch of frequencies became available for setting in Windows, going from 60hz to 100hz. I wonder if a driver upgrade from Sony inadvertantly enabled 100hz frequency, and then caused damage to the panel. Hardware issue caused by software upgrade from Sony.
3) My final theory is that there is a cable issue connecting the panel to the motherboard that can be resolved by replacing the cable. Although I centured into the case to ensure the LCD panel was securely connected to the motherboard, there was a lot of screws to get there, and I didn't feel confident going any further to access the other side of the cabel attached to the panel itself. With my Ebay search I found there are replacement cables for around $15USD, so this would be the ideal problem to have.
Also, I'm a little annoyed, when peeking into the case I noted the SATA cable was cracked at the areas where it was folded to run around the case.... This is just poor quality components inside what was respectfully a premium priced product. Maybe it's for the best that Sony got out of the PC business...