I have been using a Shure KSM9 with a Yamaha MG10x mixer with no problems until the other day it suddenly stopped working. Tried turning the mixer on/off, but didn't help. Changed the mic for an SM58 and it worked fine which led me to believe either the KSM9 was broken or the phantom power on the mixer was.

Tried the KSM9 on a different mixer, but first going into my TC Helicon GXT foot pedal (which also has phantom power) and the mic worked, which led me to believe it must be the phantom power on the Yamaha mixer that is broken.

However, I tried the KSM9 directly into an AER Compact 60 amp yesterday (which has phantom power) and it had always worked previously, but yesterday it didn't..... swapped the mic for an SM58 and it worked fine.

Why would there be an issue with my KSM9 that it is now only working in certain situations? Something broken inside where it needs more power than certain desks/amps can give or something? Is it easily fixable?

Many thanks!