Lawdawg: My box finally died last night when I was showing my brother-in-law the demo of Viva Pinata (ironic, I know). The box could withstand two whole weeks with playing crackdown for about an hour each time, and then when he comes over to see the demo, it began to freeze, I got the checkerboard video, and then the 3RLOD.
I saved the word document tutorial that you had because I knew the day was coming. Luckily I was home and had free time. Got the parts, followed the tutorial judiciously. I must say the tutorial was somewhat lacking compared to other tutorials, but if you can't follow along on this one you probably shouldn't be hacking open a 360 to begin with.
One problem I had was that I really didn't tighten the heatsinks down much at all. I tightened them conservatively with my fingers, but I believe the CPU sink was a bit off. Right off the bat after powering it up to attempt a reflow (or at least a board flex, from what someone has suggested), I got the 2 red lights, and left it on for 2 minutes. To no avail. Then, I tightened the sinks down to where they were snug (I was VERY careful to make sure that they were equally tightened and not tight at all, actually:)). I then turned it on (fans off still), and let it sit for two minutes. This time I noticed the CPU sink was definitely warmer, so the heat dissipation was there this time. I never got the 2 red lights, only the 3 lights the entire time. Shut it off, let it cool for 5-10 minutes as I grabbed a drink. Came back, powered it on, and it worked!
The heat gun trick worked for a little over 2 weeks (didn't have a 360 game until exactly 2 weeks ago), so I will keep track of the system and how it progresses with this fix in place. Starting today, Monday, April 2, 2007, I'll track my system's progress to see how well this truly does work.
Thanks again, Lawdawg. The parts numbers are a GREAT idea, I have EXACTLY what was intended and ran into no installation problems - hopefully we can translate these part numbers for those of you who are unlucky enough to not have a Lowe's nearby.