[Al Skierkiewicz]

Yes, on a rare occassion these do fail. It is a problem during manufacture. We test all of the breakers with this simple test. Turn on the robot, then lightly tap the red reset button. If the robot power is intermittant, replace the breaker. These devices are bimetal, temperature reacting, "snap action" devices. During manufacture, the bimetal contact is riveted in place and a light misalignment of the rivet press causes the bimetal to deform enough that it doesn't press against the opposing contact when turned on. This condition gets worse with time as the light contact causes localized heating and arcing of the contact surfaces.