Not enough spark

I'm not a great mechanic, but let me throw my thoughts in here. If you have spark, then the distributor and coil are doing their job. If it is a weak spark, what is the voltage you are reading at the coil? Did the ballast resistor fail and now you have no voltage at the coil? Check the whole circuit from the beginning to the end. IE ignition to ballast, ballast to coil, coil to dist cap, cap-rotor to plugs. Good luck. Doug