The first time mine died like that the ground wire on the points was rusted to the point that only a single strand of wire was still connected. I fixed it with a piece of 18 ga wire and some crimp on rings. This was accomplied with lots of back firing.
The second time the condensor was loose, so removed it, cleaned off the bit of surface rust and reinstalled. No backfiring, just died as if i turn the key off.