In case anyone else is looking for one of these, I thought it may be helpful to point out what to look for when buying second hand, beside the obvious checking the cast items are intact and the rails are straight, it seems that the 2"/50mm pulleys are somewhat delicate, as all the ones I have seen have a 1"/25mm pulley on the cable drive end of the unit on the underside, this should be a 50mm pulley to keep the correct tension on the cable, see the post's above for possible source's, the cable itself is 1.5mm dia, which is a standard cycle brake cable size, or just look for 1.5mm dia Bowden cable on the internet or e-bay, for the fittings to the cable, electrical crimp fittings will work for the spring and carriage attachment, if I find any other tips I will post on here, I am especially looking at chip and dust management as well as the tips given on the Routerforums site re the guide's.
Mike