Built in microwave in kitchen, how expensive to replace?

[Jack B.]

Tenant said that using the microwave suddenly trips the breaker. I told them to stop using it for now until I can get my guy out there. 

It's one of those older kitchens where the microwave is built into the cabinetry. Not like the modern ones, I am talking it's built INTO a hole. 

I checked my lease, the standard RHA lease for Washington state, that I thought had check boxes for what appliances are included, and apparently I'm imagining things, I don't see such a check list in there for that (just for utilities).

At the end of the day, I can always buy a microwave for the counter. I just worry about the hazard of a tripping breaker.