VHF/UHF ferrites such as the Neosid F25 are susceptible to magnetic fields. I worked ina place where production switched over to Weller TCP soldering irons, which used a thermostat based on Curie point for temperature control. We had 250 scrap assembled PCBs each with two bought in LC filters that used F25 toroids, as result of the magnetic field from the soldering iron. Fortunately, the filters had all been tested before assembly into PCBs, so it was just (!) a case of ordering new filters and waiting for them to arrive - and removing the Weller irons from that production line. As is always the case, management went looking for people to blame, and they even tried blaming engineering because we hadn't specified a maximum magnetic field for the filter! It didn't matter that the filter could not have been made to the necessary physical dimensions and meet the electrical specification.