I was doing the X-clamp replacement on a 3Rl xbox, using MkI method, and i guess i´ve discovered a POSSIBLE reason for 3RL 0020 during the procedure. I´ve uploaded a video to Youtube: http://br.youtube.com/watch?v=SJBzFJk9wjo
Here´s what happened: I´ve followed the tutorial literally. I was getting error 0102. After the replacement, BAM! 0020.
I´ve tried a few times and noticed that the posterior-lateral screw over the GPU couldn´t be thightened in my setup. Follow the video:
1 - it works
2 - just tighten half a turn of the screw, and 0020
3 - relieving the pressure, it worked again!
4 - Rinse and repeat, i can do it anytime.
All the other screws were firmly tighten, that one was the cause of the trouble.
Ah, and sorry for the sh*tty video, i made it alone and it´s hard to hold the camera AND the screwdriver *AND* keep the focus. :-D
Hope it helps.