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Gary LaPook you wrote:  There are five parts to it, a base disk, white, printed on both sides, plus transparent disks on both sides, that rotate on a central pivot, plus index arms on each side that also pivot  to align with the scales on the disks and the base.  

Thanks Gary.  I was fine on the distance side, and I could see the directions for the Course side.  I just couldn’t see which bits were free to move on the Course side.  I’d overlooked the possibility of a transparent disc.  Are you saying the inner Course scale, the one that goes from 0-45&45/90, is printed on the inner disc, the same as the D Lat scale and that the INDEX arrow and the Distance scale are printed on a transparent disc that fits over the top?  That’s very clever.  I don’t know if I dare send an OHP transparency through my laser printer without ruining it.  I think I’ll just try to make a card Distance and INDEX arrow ring to run around the Couse scale.  These cheap eBay circle cutters are very good.  We're off to Norfolk again on Sunday, so it might have to wait. DaveP