As Mr. Walker has said, oil-filled Blaster 2 coils can fail when they are run upside for a while. I discovered this in 2002 after mine failed after lap 1 in a race.

A bunch of folks in my area have been using MSD 6AL family boxes for 20+ years in various race cars and carrying spares to the track. No issues.

Have seen a few of the cars with aging distributor issues.

I had such an issue about 15 years ago.

I took my dizzy to Jerry Woods Enterprises and had it refreshed.

Good luck with your troubleshooting.