I've got a 27" iMac that's about five years old and I've noticed some dim areas, mostly noticeable on the gray startup screen. It's never been edge-to-edge bright, even when it was new, with dim edges down the sides of the screen. that was fine, I could live with it and when I'm working it's not noticeable. Now that it's older though, it's getting some sort-of horizontal larger regions of dimness through the middle-left of the screen.

I realize this is probably just age, but is there a fix for it?
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