[TheRealAnubis]

Well... yes the chips will get very hot without the heat sink.

Right, but I'm also talking about the ones without the sinks! I know that they usually get a little warm, but several of these are REALLY hot, and it seems strange since the power brick is good, the power supply is good, etc. I'm thinking there are several fried IC's in the first one, and many of them aren't socketed. I'll have to see what I can do to get them out and socketed at some point!

Why not swap the video chips and check the result?

If the first machine's video processor proves to be good you may have to install sockets and swap the ram. Since what you describe could be one or more failed memory chips.

I did swap out the VDP with no changes.. Good thinking on the RAM, though.. I was thinking the same thing and swapped out all of the old RAM with socketed new RAM. I also had to clean the cartridge port (mobo and the right angle one), brass brush off all of the IC's again, including the GROMs 1 & 2, etc. This one was pesky, but now it's working! I'm in the process of getting a donor board or two and some (hopefully) working keyboards!