I have just been practicing cleaning a junk (damaged past hope) SE/30 board. On mine the gunk under the capacitors looks like a dot of yellow right in the center. I assumed it was capacitor leakage but maybe not?
I had some success scraping away some of the gunk with a toothpick and isopropyl alcohol but some deposits remained stubbornly impervious. Curious to hear what you learn.
Having successfully de-capped and cleaned an SE/30 logic board, I notice that the original aluminium capacitors appear to have had some kind of glue under them (see image). It seems impervious to isopropyl alcohol and I'd prefer not to try and physically remove it in case I damage any tracks etc. Anyone seen this before and had any joy removing ???