XBR65X900E - Left side of panel flickering intermittently

I have an 18 month old TV that gets, on average, about 12-15 hours of use per week. Set has been great up until a few months ago when this problem was just at a point to be noticeable. It has been progressing and is more prevalent now.

What happens is that everything looks fine and then the left half of the panel will experience a shift in brightness / black level where it is darker than the right half. It may flicker very slowly, very quickly, or not at all and then just up and go away. The image is never out of focus or incorrectly shown color-wise except that it’s just a bit too dark. There is a perfect vertical delineation in the center of the set when this happens, so it’s either the panel or a controller of some sort.

Thoughts on where to look for an issue? My basic research seems to say that this is NOT a TCON board issue and may well be a failing panel. I’m happy to open it up and replace absolutely any single part in there, EXCEPT the panel (because it is 100% not cost-effective).