Motorola 21BT130BE-1 troubleshooting: Brightness Debacle!!!

[cluelessgame]

*I hope this is the correct forum for this thread*

I am going to try and restore this gem over the break and had a few preliminary questions before I dove in. Being a newer (mid-to-late 60's) set, I've decided for this set to only replace-as-needed...I know that sounds a bit lazy, and maybe later I'll go back and do a full resto, but at least for now I just want to get it stable.

This set powers up fine and reception, picture quality/geometry, contrast and brightness all seem fine - initially. The issue with this set that after about 30 minutes or so, the screen seems to get dimmer and dimmer, and bright objects blank out everything right of it. After about 45 minutes, the whole right half of the screen is black. My guess is that there's something in this set that doesn't like heat, but I don't know where to begin looking. I've attached the PhotoFact for this set if it helps.

Also, when powering down the set, the rasters collapse to a single, sharp, VERY BRIGHT dot in the center of the screen that lingers for several minutes. Is this a normal thing? I'm worried that this could potentially burn a dot onto the phosphor. Your thoughts?