I've had problems with my 6000 and it flipping the screen left/right, and the backlight dropping out too. I took it apart, cleaned the contacts, and reassembled, and no luck.
Did you clean the LCD cable connectors when you dismantled? I am wondering whether the connectors are really sensitive to dirt or grease? They also seem very flimsy, so that they can only be opened and closed once or twice reliably.