help me find an electrical gremlin, please

Steveh if I were you I'd run with what badsport is telling you. All the gm parts in the world aren't going to help you if the pickup coil is bad. They are $20.00 bucks at autozone. Noting that I'd buy it somewhere else because thats probably where you got the switch that doesn't work right. The GM stuff will give you a better spark in the long run, but it won't cure your problem if the pickup is bad.
You could test all the wires by sticking straight pins through the insulation at either end and use the ohms setting on your meter ( should read infinity). Tape over the holes afterwards to avoid more problems.