were off on the squires meet up at weekend Phil, well me and 'Cynic' are
so like I said, it is wise to unbolt the HT coil, clean up the ground lug with the black wires and clean off the stoving / paint at the mounting point, especially the bottom one that the lug is on.
having done that
Disconnect all the 6 wires from the CDI.
The using your multimeter on the loom side of the connectors.
Black probe on a clean part of HT coil ground point
Red probe on......
Orange, Meter to 200 Ohms, expect 1 Ohm (HT coil primary)
Brown, Meter to 2k Ohms, expect 420 Ohms, (Magneto charge coil)
White/Red, Meter to 200 Ohms, expect 12.4 Ohms (Magneto pulser coil)
Black female connector, Meter to 200 Ohms, expect dead short
repeat for black male connector
Any difference in the results for the two black wires may possibly be rectified by cleaning the front engine mounting bolt and a little of the frame behing the bolt head, then tighten to torque spec.
Black/White, Meter to 20K Ohms, with ignition off expect dead short, with key on expect open circuit, with kill operated expect dead short (Engine kill operation)
If all these tests are good you would be well advised to try another CDI and if so I can lend you one to prove it until you can source your own from good old ebay
If they are not good...reading higher...disconnect and clean any plugs/sockets you find along the way, if the magneto coils are reading lower, new ones needed if more than 10%...or so the book says