how to tell if a microwave fuse is bad

[sixto]

At the in-laws' house, operating the toaster and microwave at the same time blows the breaker. Been that way for decades. Today, after resetting the breaker, the microwave won't wake up; the digital screen is blank and it doesn't respond to the touch panel. I removed the case and found an 18A/250V fuse along the main wire. It has an opaque sleeve with a painted black stripe near one end. DVM reads 0.0 Ohms immediately then settles to 0.3 Ohms within 5 seconds. Is this a good fuse?

Sixto
MB-less