On a 6V IH, not much to go wrong. Leaving the ignition turned on without starting the engine can overheat the coil, burning it up. Very high charging voltage can overheat the coil, check voltage at the battery posts with the engine running fast, it should not exceed a maximum of. 7.5 volts, 7.2 is normal..
A carbon or even metal core high voltage coil tower to dist cap wire that has burned back inside the insulation for a ways and causes the spark to jump too far, can cause the high voltage winding of the coil to short internally, wrecking the coil.