Older Microwaves Are Old Microwaves That Are Fading Away Dangerous In Any Way?

Are old microwaves that are fading away dangerous in any way? - older microwaves

My mother has a microwave, which has served 16 years, until he realized that began to fade in power after this year. I've always thought that the microwave died suddenly, but it was still difficult, and requires twice the same time required for heating.

Is it safe to use this machine?
It is the fact that "Fade Away", an indication that it can be repaired?