Some homework my friend
http://www.pprune.org/tech-log/16294...-autoland.html
As far as I know you DO get the aircraft on the ground, but that's because of the GS transmitter position and angle close to the ground. Might be different in the NG.
But the question is about the retard capability. If nr1 RA fails there is no retards capability because it's dependent on nr 1 RA.