Just a comment on cleaning and fixing PowerBooks- it's frickin hard- not for the faint of heart! I got my used 12" PowerBook 1.5 last Wednesday, and it was making some strange noises when the fan came on. I knew when I bought it that it had been worked on by AppleCare- the logic board, topcase, and battery had all been replaced in early 2007. Despite this, the computer rattled loudly when graphics intensive apps were run, and the fan was running almost all the time. And the thing was running hot on the bottom. It didn't seem to hurt the performance of the notebook, but me being obsessive, I decided to crack open the sucker and clean it out. I went by this guide on iFixit: http://www.ifixit.com/Guide/Mac/PowerBook-G4-Al-12-Inch-867-MHz/53/ Let me just say first that iFixit does a great job with their instructions! They even have a pdf of all the screws and tools that you need to do the job. Unfortunately, they only have the 867mhz version, and mine is a 1.5. Kinda wish I knew that ahead of time, but it worked out well in the end- there are only a few minor differences- a few extra screws in the fan and metal framework. Since there were some scratches and dents already on the thing, I wasn't concerned with damaging the unit cosmetically. If I was working on a mint condition machine it would have been tough. First, they tell you to get the keyboard off and the topcase open- there are a ton of tiny screws, but if you follow the guide and use the screwdrivers that they tell you to use, you're golden. I got some miniature ones from Home Depot. A 00 Phillips Head and a T6 Torx screwdriver. Just be very careful because they strip very easily!! Then you pretty much take the unit apart piece by piece- including completely removing the modem, hard drive, heatsink, fan, metal framework, logic board, DC-in board and superdrive. I didn't go as far as taking the speakers out or display, but they have all of the instructions for that. Make sure that you take all connectors out using a tiny flathead screwdriver and don't pull the wires out of the plastic connectors- this would be very easy to do. My biggest surprise was that if you want to replace the hard drive or optical drive, you really have to go all the way- I mean, you're pretty much taking the computer completely apart to do (what should be) a simple hard drive replacement. I know they fixed this on current Macbooks, but anyone working on a Powerbook should know this. I cleaned the fan, ducts, and the heatsink out with a can of compressed air. Then put it all back together and made sure each screw was tight. Some of the screws holding the topcase and heatsink in place were definitely loose. The heatsink's light blue thermal putty was applied in a square sheet and was improperly folded over so it wasn't flush on the graphics chip. I remedied that by carefully folding and molding the putty square back into place. One thing I can tell you is that when sliding the heatsink back into place, the thermal putty can easily be pushed and folded back- this is a very delicate maneuver that obviously even the AppleCare tech didn't get right!! In the end, I got it all back together and it runs cool and the fan doesn't make the noises it once made. I'm so happy that I didn't screw it up, because with all of the fragile connectors it would have been very easy to damage the computer. If you try doing this, be very careful and leave a few hours to work on it. This is a great project to do, but you really have to know what you're getting into. I have dissected and cleaned many PC notebooks, but this was by far the hardest I've done, and the easiest to unit to damage. I don't know if I would recommend this to anyone, but I'm sure glad I fixed it- thank you iFixit! I'd like to know if anyone else has had the thermal putty issue with their PowerBooks- I read here that some people had the same issue in MacBook Pros.