1971 Scamp limited....

Good goin' To check for spark problems,

Remove the connectors from the ignition box, distributor, and ballast. Inspect them, and work them in/ out several times to "scrub" the connections clean, and to "feel" for tightness.

Inspect the interior of the distributor, for rust, debri, and strike damage. Check the gap in the reluctor (.008" that's inches not mm) with a BRASS feeler, available at O'Reallys

Hook your multimeter, on low AC volts, to the distributor connector and crank the engine. It should generate about 1V AC

Remove both the ECU box and voltage regulator, scrape the rear of the box mounting clean, and scrape/ grind the firewall around the bolts. USE star washers, and consider adding a ground lead, "daisy chain" over to the engine block. No14 wire is OK, 12 is better

To temporarily simplify potential wiring problems, make a nice big no14 clip lead, and jumper from the starter relay battery stud to the coil + terminal

Remove the coil wire at the coil, use a grounded probe, IE clip lead and screwdriver. With your jumper hooked up to the coil, you now have hot battery to the coil. Crank the engine (jumper the starter relay) and see if you have spark.