page 3:
z=0.24671 ref Carilli et al 1992 (not Darling 2004)
1 mas = 3.87pc (not 4.8pc)
(added a reference to the web-based cosmology calculator)
page 3: footnote removed; this info is in Table 2.
page 9-10, section 7: expanding the discussion of the
fitting of helical jets.
Added Figures 8 and 9, and Table 6.
page 5, added description of components; insert Figure 2