When the arrestors are grounded correctly, they can sustain multiple "indirect" lightning strikes and power surges for up to 10kV. They are certified with IEC61000-4-5 industry standards. Keep in mind that the arrestors cannot survive direct lighting strikes.

The arrestors are not designed to be serviceable. The part inside the arrestor is a "gas tube". Even after replacing the gas tube (assuming that everything is reassembled correctly), you would still need to test the arrestor's Voltage Standing Wave Ratio (VSWR) using a Spectrum Analyzer. Due to the complexity and cost involved we would recommend directly replacing a unit suspected of being damaged by lightning or power surges.