Yep I had a similar experience, the breaker was shot and replacing it (over $50! just for the part) solved the problem. In my case the breakers were snapped onto the rails inside the service box. It was really easy to switch it out once unscrewing the fascia . Recommend you throw the main breaker first tho if you can. Good luck!
Power Consumption and Breakers
I live in an apartment building in San Fransisco where I keep blowing a circuit breaker (the only one to my apartment.) I just got a pair of Audio Research Ref 600 Monoblock amplifiers. They play for 30 seconds or so and then I lose all power. I have a landlord who I do not enjoy asking for anything as she is slightly off the wall. What are my choices other than moving or selling the amps? More info... the building is over 100 years old and she probably will not allow me to re-wire.