Spark is created when the points open, if you take a screwdriver and break the points from the closed position do you get spark? If not run the driver down against the plate while it is layng against the movable point, and move it away from the arm, did it spark then. If so the points are oxidized and not allowing a circuit to ground thru their contacts. They can be cleaned by running a point file thru them, dont't go crazy as they are only flash coated with tungsten or platinum. If all this fails I would guess you have a bad condenser, which can be checked with an ohm meter. No continuity between the lead and the can. Hope you can understand this and it helps.