Mark, The circuit design and components on the PS-2 Power Supply board are much different, then the ones on the PS-3. Let alone the processor and software differences.
So it could very well be that it is causing issues with the PS-3 processing DCS signals while the power is not a clean AC signal.
Did you do a signal strength test on your J while at the home of a friend?
The hanging issue is why the TIU isn't working on just FIX 1 or is it?
My Z-1000 brick states 18V output for 100W. 25VAC is high, even unloaded in my opinion.
Did you test your TIU with your friends Z-4000? Did it work on his layout?
This could be a bad brick. G