so what you are saying is that you replaced the main control with a used main control?
I would say that if you can switch the drawer controls, yes you could have a bad control.
Do you mean with the control in the bottom drawer, your F1 magically goes away?
yes - the F1 stops. I'd read that an F1 on the top drawer only indicates no power to the bottom drawer and the usual suspect is the heater plate thermal fuse or power resistor. However I've eliminated those two items. Leaving a question mark hanging over the controller. Switching them has confirmed at least that something is wrong with the bottom controller.
I guess what I'd like to know is is there any knowledge or experience out there on troubleshooting the controller itself and performing a repair if possible. Perhaps a capacitor or some other part is known to blow. In which case I'd much prefer to repair myself with resources at my work than purchase a whole new controller board. I have visually inspected the board and ruled out any obvious burn out.
Also mentioned in cases of top-drawer-F1 is to check the coils - the inlet and outlet etc but I'm not entirely sure of the best way to test these so any info on that would be great too.