Quoted from Sciddleybop1980:The opto switches aren't registering the targets have dropped. Check to see if the plug is on correctly. Check for cold solder around the header pins.
Unusual for all 3 to stop at once. See if they register in switch test.
Physically check the optos an inspect them. And ensure nothing could be shorting them and causing a fuse to blow. Check the plug at the board end and ensure it's correctly seated.
That's what I'd do to start.
If all seems well. You may have dodgy optos.
Of course a far more knowledgeable person maybe able to give A better suggestion.
Good luck
I cleaned the optos and now it's working, so hopefully that was an easy fix!