Circuit Breaker Keeps Tripping?

I'm renting an apartment. I've had this stackable washer/dryer set since January of this year; all of a sudden both stopped working. I had the apartment manager call an electrician and it was the circuit breaker that tripped. He went to the locked basement and took care of it. I did laundry and all was well... for 1 day. The next day I went to use it again, neither worked. He came out again made whatever adjustment and it worked until...

you guessed it the next day. 3rd call to him, he says he's 99% sure it's the appliance. I'm not certain that's an absolute fact. The appliance doesn't cut off while I'm using it and I'm not sure what else is using that breaker. It is now summer time, perhaps the other unit has an AC on that breaker as well, it could be anything.

The basement is locked so I can't get another opinion. Can anyone pass along some words of wisdom that I can use to convince him to check further into it? I'd hate to replace a washer/dryer set unnecessarily.

By Fanci