Does a circuit breaker go bad or get weak?
It doesn’t start tripping at a lower level than it should, unless a loose connection/contact in/under/at it is making heat that throws it off. There are cases where the handle of the breaker mechanically will not reset, but it is more common that failure to reset is from a short that is retripping it immediately or is from the person not knowing the right procedure for resetting. Of all home wiring problems, breakers get a lot of suspicion, and only a fraction of it is deserved.
