So color me wrong..A failure rate of 1 or 2 out of 1000 syncro spark circuits is pretty remote, but possible,,....I haven't (or won't) use 1000 syncro spark circuits in the foreseeable future, as most of my ignitions use mechanical advance..The failure rate of my sensors is so remote they're put into the engine with 5 minute epoxy..Usually the problem is a loose wire at the solder joint caused by flexing...The turn on/off test has always worked for me....
FWIW, the BME pickup is solidly mounted and flex is pretty remote...
My circuit has
One toroid coil, (6 wires) 3 diodes, 3 or 4 resistors, 4 capacitors, a TIP31C and a N6241 thing...Which is the amplifier ?
Sometimes when a circuit is bad I can replace the 6241 and it works again....