Raw, how many times has the breaker been tripped? How old is the beaker? I ask because a lot of people are unaware that beakers age, and they should be replaced if they have been tripped more than five times, each time they are 'opened' they open easier and easier.
It's worth a shot, and if you get your problem solved, don't forget to replace the breaker anyway, because it's been 'tripped' a few times now.