Looks like I'll have to rebuild the power supply. The -5V has dropped to -3.6V. I don't think anything other than the rs232 serial port uses it.
However, I now get a kickstart prompt, but it doesn't load the kickstart disk. Hopefully it's not the 8520R2 cia. I'll try re-seating those again and hope for the best. I guess there are still a few of those available.
I just realized that the piggyback ram expansion that I had added isn't the one from Amazing Computing. At least not the original article. The motherboard modification part is the same but mine also has modifications to the daughter board. There are two 74LS series chips added, a bunch of jumpers and the DPALCAS and DAUGCAS pals were replaced with versions from C-Ltd.
Anyone familiar with that mod?