Stab-Lok breakers made by Federal Pacific don't trip reliably: if at all.
The rule in real estate sales is: if it isn't broken, it doesn't need to be replaced. Well, this doesn't account for systems that have a certain life-span like roofs and decks, or safety devices like electric panels and thermostats in water heaters. We don't know if these "work" unless tested in an emergency. Then there are HVAC systems, whose effective and safe operation depend on their fuel source and initial quality.
The buzz on these Stab-Lok panels is that, at the least, 20 percent of the breakers don't trip when they are supposed to (usually when 5 times the rated current passes through them). One electrician told my that he shorted a whole panel to a steel beam and none of the breakers tripped. In this house there were multiple scorched receptacles, so a fire was a constant hazard due to this panel. And, yes, being wet didn't help either.