GE Spacemaker - above my stove and has the light, fan, etc.

I was heating a cup of water and thought I heard a crackling sound coming from the microwave, which then stopped. I turned the microwave off, but then turned it on to again heat my water. Everything seemed to be working fine, but the water was cold after two minutes.

It was manufactured in 2000 - does it sound like it is worth repairing?? Thanks!