the mixer has been in one of my two kitchens since 1988 without fail;. The other day they called and said it was making a noise but then it quite, (never a good sign) went back to working everything good, Yesterday I received a cal saying that it had made a lot of noise they turned of then.
A brand would help. But if it’s a planetary mixer, sounds major.
I suspect you probably have a Axis. If so it is a all gear driven machine. That means you have probably suffered a bearing or gear failure. Or perhaps a gear change index problem. Doesn’t really matter, as it will have to be torn down to determine the full extent. And it’s not arepair you will make in one or two days.