I might add that you should be very careful if you insert the dark slide with the back removed from the camera. The slide needs be inserted straight to avoid possibly cracking the faceplate that makes contact with the camera body. The faceplate is secured to the back by 4 screws, I think, one in each corner. Inserting the card at an angle can crack the faceplate, usually near the screws on the side of the slide opening.
I got a heck of a deal on a box of Bronica SQ-A equipment, but I think 3 of the 4 backs were cracked from the dark slide being shoved in crooked.
Dave