problem with dual point no spark

It just takes a little back and forth. With the distributor in the back it's hard to see the gap and it's easy to accidentally prop it too wide by twisting the gauge or catching the tip on a screw head. I usually mark the base to preserve the timing, pull the distributor and put it in the bench vise, then gap each set of points, put it back and check the dwell. I have a small chunk of balsa wood in my toolbox for propping points open, so I can check the dwell for each set separately, and then the total. I usually wind up with one set at the wide end of the range, and the other at the narrow end, and the total right in the middle.

My initial reaction at seeing the original "no spark" post was to check the ground wire on the breaker plate. Since this flexes every time advance comes into play, it can fray pretty badly, and even break. I have had to replace it a couple of times over thirty-some years.