Well the first is probably due to impedence differences....Only discrepancy was when I had my multimeter on "2M" it read 0.8, which should be 800k. When I put it in "200K" mode it read 138k. Weird.
magneto:
blue (mine is green) to white: no reading
blue to black: no reading
white to black: no reading.
The magneto being an open circuit is probably your problem - but it does seem odd that both side are open. What's your meter set at?