Repeated tripping on reset box

I work in a building with 13 yr old air handlers and i keep having an issue with power loss.. ahu trips out repeatedly... First thought was that the motor was over amping so i checked for belt tension being too tight and amperage. In which i seen no issue... 3rd time that i found the unit tripped out i went straight to the reset box mounted on unistrut next to the disconnect and the vibration of me slapping the outside of the reset box caused the unit to kick on... 2 hrs later i went back to the unit.. and it was tripped out again.. only thing similar ive seen like this in commercial building maintenance is a weak breaker .where a 20 amp breaker would trip when only getting 12 or so amps...So... That being said my thought is that ....its a weak reset box that needs to be replaced?? Thoughts??

source https://hvac-talk.com/vbb/threads/2243958-Repeated-tripping-on-reset-box?goto=newpost