Filament runout sensor are usually just a microswitch with a lever with a roll which gets pushed towards one switch state when filament is present, and by releasing the lever when no filament is present, the switch changes to the other state. Those levers are thin metal and bend easily. Fix ist simple too: Open the sensor enclosure, bend it into a position that it reliable switches when filament is inserted.
I say “usually” because I haven’t opened up the SV08 sensor yet, and I simply assume this to be the case with those too. Alternative detection methods do exist, but are at this time less common.