Extruder 1 not laying down filament but extruder 2 is?

In duplicate or mirror mode the extruder in head 1 which is not clogged and drive is working will not deposit any filament but head 2 is?

I was wondering if I can take more detail. Does the head 2 work in other modes? Go to the feeding function interface and try if it extrudes normally(this tests the motor)? Can I have some fault pic or video to learn more detail?