These panels are widely regarded as a fire and electrical safety hazard, dangerous for a number of reasons. Over the years I’ve personally seen Federal Pacific breakers fail to trip when they had a solid short circuit, and I’ve seen handles in the off position and found the breaker was actually on, with the circuit live. Either condition can kill a person or start a house fire.
It’s hard to overstate how serious a problem these panels and breakers can be. If you own one, replacing it is likely one of the biggest safety improvements you can make.