I try. If the alignment is constantly changing so the pads start rubbing, I'd say you're getting dry/sticky seals. How old's the brake? Has it been ridden much in the rain? If it gets very wet, then the pistons corrode where the seals sit, and this may be the cause of this problem. I was going to do a video guide, but my Dad was away with the camera when I last rebuilt my brake, but I'll right up a wiki thing tommorrow and post a link in here, might help.