Montgomery Ward 1985 information?

[MK1234Tfan]

Hey guys I have a Montgomery Ward 1985 set I recently acquired and would like to bring it back to tip top shape as it's my oldest set. Only problem is I can't find ANY information on the set at all! The model# is GGD 12305
I'm having a problem with the brightness knob that when I go to adjust it, it kinda goes dark then bright. So I figured why not check the potentiometer. Low and behold it doesn't say the value on the potentiometer so I can't check it. The only thing it says is:
52z
116d
500b
I've tried looking up any info on these numbers and found nothing. Also seems to slightly change color while I'm watching it too.
If anyone has a schematic or any information at all on this set I would be greatly appreciated!