I had a couple HR's on my old route. We had a troubleshooting tool that had a bunch of alligator clips on it that you hooked up to the safety string check points in top or bottom Jbox. It would trap the switch that opened and light an LED which helped pin point the problem switch. It could be a number of things though. Its been 5 years since I've had the pleasure of pulling steps, sure don't miss it.. Lol. You'll find it, just keep after it.
