"Specs say DC"
Thats why I'm asking about a manual & better photo; clues to operation. Will it see breaks? actual shorts? both?
Feeding dc to the track shouldn't be a big deal for a test. A wall wart, 9v, or lantern battry should get some result (depending on the amps it may use). Half wave from existing track power (diode) will likely bounce the needle, but still work.
I'm guessing the reader just contains a magnet, and don't recall how the coil bit was set up. It likely just uses a different coil for each voltage level. The magnet likely points to the magnetic field created at a short is my guess. Some searching may even yeild a plan for a homespun version. (instructables site or youtube?)
