This morning I was finally ready to disassemble the Spencer. I put it on my workbench but had one more idea when I saw some brass punches.
I decided to take a brass punch and try to tap the slide forward. With very light tapping with a plastic hammer, the slide began to move forward. I think the whole problem was lack of lubrication. The inside of the gun was very clean, but very dry. I have been lightly oiling the parts I can see and the mechanism is loosening up. It's not all the way there, but I think with some more gentle movement of the slide, the Spencer might be back in business. Thanks for your thoughts and help, I'm so glad I didn't have to take it apart. Daryl