I seem to be having trouble with this too - not getting the MK1 to output its power. I've changed the throughput settings and rotated the yellow arrow to no effect.
-edit- Solution found!
I had remapped the hotkey for changing output direction to ALT-R. What confused me is that my 'rotate object' hotkey is R. So when I hovered the mouse over the yellow arrow and hit R, it would rotate the arrow but that doesn't actually change the output direction. I had to hit ALT-R to change output direction!
The sad part is: this isn't the first time I've forgotten about this lol