re: Upper ice maker stopped - Solved.

If it's freezing up chronically. You'll likely need to replace a thermistor or the control board. Obviously in forced defrost the heater works so you know the heater and the defrost thermostat are good.
In my experience with frigidaire. The defrost thermistor fails and gives the wrong ohms reading to the main board. The machine can't tell its icing over. The upper icemaker stopping is step one. Step two is the freezer ices over and needs to be manually defrosted.

If this problem returns. You will need to have someone check the ohms of the thermistors at the control board. If they are in spec replace the control.
On your fridge it's behind the air vent at the front bottom left side of the fridge.