Not to butt in on any of Bruce's work, but have you checked your points to make sure they are working properly (reading ohms with points open/closed). Sometimes points get a piece of dirt or corrosion on them that prevent them from "closing" the contact - in otherwords they read "open" all the time. On the same hand they can read "closed" all the time too.
Also, have you checked or changed the condenser? This will also cause no spark problems. The condenser requires a special instrument to test the condition.
