If it's never been disassembled the plate should be there.

With an adjustable sighted version, the sight has to be removed from the base. Two set screws securing the base to the slide have to be removed, then the base driven out. Some/many are pretty tight, so a wedge of some kind should be inserted into the base in place of the sight, so the base isn't bent upon removal. With a Novak, just loosen the set screw and drive it out. I haven't had a problem with the rear Novak being overly tight on any of these. On the other hand, the front sight is another matter.