If you have points, close it, then with the tip of a screwdriver open it and let it close by itself. If you get a spark at the points, then your coil is OK. If you do get a spark at the points, then replace and reset the points along with a new condenser. If you don't get a spark at the points, then your coil is most likely shot. Be sure to do all this with the key in the On position.