Well I'm not that good at memorising.
The pin on the darkslide fits in a slit allmost at the bottom of the filmback. It pushes a lever aside which in turn activates a lever in the camerabody. Maybe one or both of the levers are stuck. In that case perhaps you can exercise it with a needle or something similar (someone, correct me if I'm wrong). You can see it if you remove the filmback.
Cheers Søren