Mine doesn't have the Citizen shutter, but there should be a lever somewhere around the shutter to set X sync as opposed to M or FP. Second, perhaps the cold shoe is shorting the contact on the bottom of the flash. Try putting a bit of scotch or electrical tape on the inside surface of the cold shoe to insulate it. Third, pc connectors often get loose or corroded. You could try cleaning the contacts and very very gently squeezing the outer ring on the flash cord contact for a tighter fit.