Intermittent ignition spark

I did not notice the cap button. "Something" caused that. It may have been wear, or it may have been something else. Check your plugs and wires for opens. Was it arcing anywhere such as a plug boot before this happened? Missing occasionally? Also check the rotor carefully for "punch through into the shaft area.

Also if you go to the MSD website there is a test procedure there. Examine the interior of the distributor for shaft wear, debri around the pickup/ trigger area, and heavy rust.