Problem solved!!
Yes, the Ektalite panel was missing, and there were no shims or bosses creating the correct spacing. I don't know how the previous owner had properly focused, and since it's been a couple of years since I've used the camera, and the focusing errors had been somewhat masked by stopping down the lens, I was quite unaware of the problem until I used the service manual in disassembling the focusing panel.
My local used dealer really came to the rescue. In "the back room", he has a good sized box of various parts for Speed Graphics, mostly brackets, etc. He also had one each of new-in-the-package ground glass and Ektalite panels. I bought both, and cleaned and installed them. I noticed that the original #2-56 screws had damaged slots, so I ordered a bag of modern hex-bit #2-56 from McMaster Carr.
I test focused the installation using a 4x loupe, and the images were really sharp. So, this one gets taken out soon for some work. I have a number of lenses mounted on lens boards, ranging from 90mm WA, to a Fuji 400 T. Lots of possibilities.
Thanks for all the responses!!