Vent: a chafed wire in a wing root ate 3 days of my life

Had a squawk on a King Air 200 for a right nav light that kept dying and coming back. Pulled the wing root panel expecting a loose cannon plug, but the pins were clean. Spent a whole shift buzzing out the harness with a Fluke and got nothing, so I started blaming the light assembly itself and swapped it twice. Turns out a wire bundle had been rubbing on a rib clip for years, and the insulation was worn through right where the bundle bends around the spar. The break only showed up when the wing flexed a certain way, which is why my meter read fine on the ground every single time. Took me 3 days and a lot of hangar coffee to find a spot about the size of a dime. Now I run a flashlight down every bundle I can reach on inspection, even when the squawk sounds simple. Anybody got a trick for finding chafe spots that only show up under load?