If this is the first time coil has given you a problem then it is probably just an age issue.
Distributor system coils would often run too hot and fail early, the solution to this problem was to reduce the voltage at the coil by a few volts, i.e. 12v down to 8v.
This reduces the coil heat significantly.
Manufacturers would install a Ballast Resistor on the 12volt "+" coil wire, to reduce the voltage.
You can do the same.
It does reduce spark voltage which isn't an issue most of the time, but on cold engine in cold weather, a hotter spark might be needed.
So what the manufacturers also added was a 12v wire from starter motor side of starter solenoid to the "+" on the coil(with Diode), what this did was to give the coil 12volts only when starter motor was being used, so hot spark for starting.
On 4 post solenoid, that's what the 4th post was for, the "I" post goes to the "+" on the coil, "I" has 12v when starter motor does, no diode needed.