Mythos Grinder Not Grinding

Hey! I’ve been using a Mythos grinder for the last two years at our coffee shop. We grind about 20g at a time and set it to be fine enough to extract at between 26-30 seconds. When we set the grinder fine enough to extract the espresso in that time, the grinder doesn’t grind. I hear the motor working but the burrs aren’t spinning.

Does anyone know the cause of this? Is it a motor problem or something else?