See row of red LEDs on M8391? On power-up the leftmost LED lights and
goes out. Then the rightmost two LEDs light and stay on...
I can't remember exactly what mine does, but I do remember 2 LEDs at one
end being on when it settles down. So I think yours is probably OK.
Of course I don't know mine works, I need to get a working TU58 tape...
-tony