A perturbed orbit resonant scattering theory for pitch angle diffusion in a 'slab' model of magnetostatic turbulence is slightly generalized and then utilized to compute the diffusion coefficient for spatial propagation parallel to the mean magnetic field, K∥. All divergences inherent in the quasi-linear formalism when the power spectrum of the fluctuation field falls off as k-q (q?2) are removed. Various methods of computing K∥ are compared, and limits on the validity of the theory are discussed. For 1<q<2 the various methods give roughly comparable values of K∥, but use of perturbed orbits systematically results in a somewhat smaller K∥ than one obtains from quasi-linear theory.