80s Philco-branded Philips 13" - Very dark screen

[YamahaFreak]

I have rescued a 13-inch Philips (Magnavox) CRT TV set, probably built in the mid-90s (build date is obscured by wear on the label) from an abandoned motel. I kept it mostly because of the curiosity of the set being branded Philco, despite that brand having ceased television manufacture decades prior. After thoroughly cleaning the TV and checking for any obvious signs of trouble, I plugged it in and powered it on. All seems well, but the picture is extremely dark, to the point of being almost totally black. I tried adjusting the flyback G2 control, and although this did produce a picture, it was very washed out, as though something before the flyback is keeping the picture dark. I also tried adjusting the sub brite control on the board, to no avail...I am out of ideas. I returned the flyback to its previous setting, to avoid any undue wear.