Don't forget it could be the brake pads have worn down. Bleeding won't fix that, as you probably know. There really isn't any adjustment for these disc brakes.
If nobody else gives you some good instructions, I'll do so later -- just don't have time right now.
You could look up brake bleeding for scooter on youtube. There's probably many videos on it there -- maybe even for your model. Any model close would do, though.
