help me find an electrical gremlin, please

I don't know if this works with some of the import/ aftermarket relacement ECU's but the originals could be triggered by shorting one or the other of the dist. connections to ground. This at least would check the rest of the system in a rudimentary way

The simple answer to the pickup gap is, if you get it too tight, it will strike and damage the coil/ reluctor, and if you get it too wide, it won't generate enough voltage to trigger the ignition. I suspect this gap depends on how good the pickup coil is, and how strong the magnet is.

I found one tune-up guy who CLAIMS to have replaced several pickups which evidently had weak magnets. I don't work with enough of these to get a good enough sample.