My 99 Camry has an intermittent problem with the starter system. Sometimes I turn the key to start and nothing. After repeating once, twice or three times it will start up normally. I have rebuilt the starter and solenoid and those are should be fine, The battery is healthy and system properly charging. Being intermittent I can't easily trace this and expect failure at the worst possible time like at the parking lot at in a shopping center 20 miles from home. I would prefer to preemptively repair this but don't want to do the unnecessary. From what I see it can be either the neutral safety switch or ignition switch. I am leaning toward the ignition switch since I have never had to diddle with the shift lever as I would expect with a bad NSS. Any idea how I can definitively determine the culprit before failure?