* The coil can break. The coil is the heart of the pickup, and it is responsible for generating the electrical signal that is sent to the amplifier. If the coil breaks, the pickup will not work.
* The magnet can break. The magnet is responsible for creating the magnetic field that interacts with the strings to generate the electrical signal. If the magnet breaks, the pickup will not work.
* The wiring can break. The wiring connects the coil to the output jack, and it is responsible for carrying the electrical signal from the pickup to the amplifier. If the wiring breaks, the pickup will not work.
In addition to these physical causes, magnetic guitar pickups can also be damaged by environmental factors such as extreme heat, cold, or moisture.
If you think your magnetic guitar pickup is broken, you should take it to a qualified technician to have it diagnosed and repaired.