Quoted from barakandl:Needs to be a 555 bulb. Not enough load from an led.
Quoted from KenLayton:Yes indeed! This is one of those rare instances where an incandescent bulb absolutely positvely MUST be there. An LED bulb simply does not draw enough of a load for the Q25 to properly latch. Without a properly working solenoid expander board, the wrong coils will be firing!
I used an LED in my SEB on EBD and it worked fine. I guess it all depends on the LED and the tolerance of the SCR. Couldn't hurt to try.