An attempt is made to provide accurate results for the elastic spin asymmetry parameter in the energy range 0.14-300 eV. A comparison of the present work with other sophisticated calculations at 54.4 and 100 eV shows a significant difference which is attributed to the importance of including exchange couplings to all target eigenstates even at energies as high as 54.4 and 100 eV. A comparison is also made with the experiment of Fletcher et al. (1985) which measures the asymmetry parameter at 90 degrees . The present results support the general pattern of the measurements although there is some concern about the details. Unfortunately the error bars on the experiment are too large to permit any definite conclusions on detail to be drawn.