Why would my electric turn coordinator suddenly stop working?
The motor for the gyro in a Turn Coordinator runs off fixed frequency ac power. For this there is a circuit board in the unit that includes a solid state static inverter to convert the airplane's 12 vdc to ac (110 v at 400 hZ IIRC).  When they just die like that it's usually because the inverter or something else on the circuit board has gone south.