Yes, you have to take off the frame. Then take off the timing rod. The guides teaches you do that. Once those are off, get a 1/4in 12-point socket and unscrew the screw that holds the vertical adaptor in place. Install new one, tighten screw down. Reinstall the timing rod and frame and your done.
Also, when unscrewing the collar from the timing rod shaft, count how many turns it took to unscrew it, so when you go to re-install it, your timing will still be in or around the same place.