How do you remove a clutch drum assbly on a model TB25CS?

I have a Troy-Bilt model TB25CS and my starter string will not recoil; therefore I beleive I have a broken string Recoil spring. I have the shaft removed from the housing, but I cannot get the clutch assembly off. I can see a star screw inside the shaft, but the motor turns when I try to remove it. Any ideas?