Thank you very much for your reply,
I thoroughly cleaned every sign of oxidation, removed it with a fiberglass pen and reapplied the solder-mask, as in the images below
I also did a recap of the power supply and now the voltages when the computer is on are 4.88v / 11.67v / -11.40v / -5.08v
I also noticed something. If I restart the Amiga 2000, when it's hot and has the graphical glitches, it doesn't load the Kickstart but goes directly into guru meditation, but if I insert a Buddha IDE, which has a small RAM expansion on board, it loads the kickstart, but still full of artifacts. So I'm starting to think that there's some ram module that doesn't work well or at least some track related to memory management. Unfortunately I don't have a DiagROM to be able to test.
What do you think?