I have the same problem and so far I've only got to the point of getting the amp head out of the cabinet. You need to take out all the screws on the top, including the handle and two screws on the right and left side of the cabinet near the back. Then you have to take the 15" speaker out and disconnect the leads to the LED light, speaker, and tweeter (if you want to pull the entire amp head out).
Hope this helps and if you find out how to fix further, let me know on here. I'll do the same, I'm delving further into it today.
Matt Browning, April 2008