Mysterious Electrical Issue

There are a lot of circuit tracing units on the market, some use the power of the circuit some are self powered, some are used to trace signal or voltage some are to check continuity. They run in price from just a few dollars to like my substructure pipe and cable locator, several thousands. Harbor Freight has cheap imitation models while online you'll find some really expensive models. I have a mixture of both. Graingers(expensive) has some great professional models.

If you have any experience circuit tracing you're good to go, if not we'll help but my way usually is the long way and some guys on here know great shortcuts.

How about it fellas, got ideas for him in meters to use and how?