Siggi, indeed this unit has OPT 6,9, CTT, WR and GPIB so both CTT/WR board and GPIB are installed.
As I received the score with PSU dead and removed with all cables loose, I used the Option service manual to reconnect.
Indeed every cable seems to be in place but for sure there might be one cable missed or mismated.
Unfortunately the mechanical assembly diagrams are not specifically enough to see which interconnect cable go to which connectors.
I should follow-up on your suggestions and trace out every cable, focusing on the trigger signals.
I hope other mavens can add to this.
Bon soir¨¦e
Jon
Jean-Paul