Not really a hardware problem, but I'm just so jazzed I had to share.
For a couple of years now my A3000 hasn't been working. Intermitant or no boot/black screen, other problems like graphical glitches, etc. I finally took the advice I see here so often and cleaned contacts, re-seated chips, etc. and now it's working 100%! Why I'm so happy is because I bought this machine new in 1991 or 1992 so it's been in the family all it's life.