How'd he think to look for a break in the insulation. Did he perform a test?
My money goes on he checked continuity at well head, finding an open circuit. Then he physically ran his hands along the wire till he felt abrasion in insulation. The break was located where insulation was worn away. Add in a crimp on butt splice and problem solved. Above ground, the sides of the break connected against each other, but when dropped down the well, the weight of the wire below pulled them apart.