Sorry I've been away, did you get this fixed? I fought problems with my +12V sense line going to the MSD getting grounded out and not letting her start up, especially when she was still hot. Turned out to one time be a chaffed wire touching the intake, then a corroded wire that had high resistance through it that would drop the "sense +12V on" voltage and not let the MSD fire. It is possible with your broken ballast resistor or spade terminals on it with even a little corrosion you were dropping your sense voltage enough that the MSD didn't think the key was "on" so to speak. Hope you got it fixed Good luck.

P.S. I meant 12 V in my previous post as well... I deal with 24V a lot at work and just auto piloted that voltage when typing, oops.