Hi all,
I managed to find a wiring diagram for the EL series 2. It's in German, but I used an OCR program to translate it to English. It's not perfect (its tried to translate some of the other bits of the image unsuccessfully) but it gets the point across for the functionality of the pins. Hopefully this will help someone in the future.
The extra pins (on the 5 pin connector on the far right) I think were used for the remote control unit (intervalometer) from Bolex. One of the pins notifies you every time a frame elapses. The other is an emergency stop. I'm assuming the process for firing a single frame is:
Listen for a 10v 3ms pulse on pin 4.
Bridge pins 1 and 2 to run the motor.
When a pulse is fired on pin 4:
break the bridge between pins 1 and 2.
run 12v to pin 5 to immediately stop the motor.