You can use a visual fault locator (VFL), which is a device that emits a red laser light through the fiber, to trace the cable and spot any breaks, cracks, or bends. Fiber optic cables are the backbone of modern communication systems. They deliver enormous volumes of data through strands of glass thinner than a human hair. Later, comparisons can be made. Start with the simplest, fastest checks (visual inspection, cleaning, cable routing) and only move to instrumentation (power meter, VFL, OTDR) when those steps don't clear the fault.