Possible graphics chip failure; powers up, DVD stuck: Help, please!

Hi, thank you for reviewing my question.

I was so excited when I first got my G4 iBook; sad when it first started to fail. I went to the local affiliated computer repair place, Computer Loft in Boston, and they told me it was the logic board. OK, I had them replace this... twice. The third time it failed I decided I might explore the problem a different way.

I read up a bit on why it could be turning off, going to a blank screen and failing to do anything. It looks like there was a common problem with this model of iBook with similar symptoms: graphic card failure. I looked at how to adjust this and there was a site that recommended putting a shim in the computer between the case and this chip. I looked at where this shim was supposed to go and it looked like it would be just to the left of the touchpad. I applied pressure to this point with just my fingers. Amazingly, the computer starting working again! ...for a little while.

When it stopped working again, I went out and got a HP desktop. This was a couple of years ago. The other day I pulled this iBook off the shelf. I thought it was a G3 I also have, totally different story- For fun, I tried the finger pressure stunt again. It worked! In a couple days, it was starting to go to a blank screen and shutting down every once in a while. The fan acting up? I did not hear the fan going and it was feeling quite hot, but I had not used it in a couple years, so I did not think too much about it. I just rebooted it & it seemed OK.

Anyway, my girlfriend got a couple DVDs from the library and we started to watch them. It shut down during the while the 2nd DVD was about to begin. Now I have library material due in 2 days that is stuck. I do not want to break this machine apart, but if I do I would like to do it in the best way possible. Suggestions?

FYI: I did install a hard drive on a G3 using the guidance provided on this site, so I do have some sense of what to do if pointed in a good direction.