I didn't know which pins to treat as B, C and E, so I just took some measurements:
Red probe on 6: 0.61V between 6-5 and 6-4. OL when black on 6.
Red on 5: OL between 4 and 6. Black on 5: 0.61V between 5 and 6, OL between 5 and 4
Red on 4: OL between 5 and 6. Black on 6: OL between 4 and 5, 0.61 between 6.
I hope that's useful.