Occasionally the planets align, fate smiles on me, and everything works out. Boy, that happened in this case.
To summarize, I bought a Wavecrest DTS-2077 Communications Signal Analyzer. It's an amazing piece of equipment that can measure time intervals with a hardware resolution of 800 fs. Yes, that's femtoseconds. Of course, it has to be working - mine wasn't. I thought the nonvolatile ram chips might be at fault which is what started this thread. But I decided that before I performed surgery on the chips, I'd try everything else I could think of.
One of the things I thought of was to pull the processor and inspect it and the socket. This is an old 486DX2/66 in a non-ZIF socket. When I pulled it, this is what I found:
That pin has probably been bent since the board left the factory. Look closely and you can see a spot of green corrosion between the metal plate and the bent pin. Nothing helps a processor more than occasionally shorting one of the data leads to ground. The pin touched the socket as long as the processor was pushed down tightly but any vibration or jarring could shift the processor and break the contact. I carefully straightened the pin, reinstalled the processor and put everything back together. It worked!!
Here's a picture of the unit measuring a signal derived from it's own clock. Not very useful, but it shows the internal noise and jitter of the unit.
No lottery tickets for me - I've used up all my luck for this year.
Ed