I can't find an answer to this: maybe it's buried among posts where people have the opposite problem.

My SQ-AI and SQ-I back used to work perfectly, but now I can release the back even without the darkslide in place. When the darkslide is in, the camera won't fire and the red light comes on, so that's working normally.

Is this a problem with the camera or the back?

Looking at the back of the camera, there's a pin bottom left by the release button. It can be pushed in, but it springs back.

Looking at the back (film side towards me), there's a pin bottom right (that mates to the one bottom left of the camera). With the darkslide in, the pin pushes out towards me. It retracts when I remove the slide.

Hoping I can sort this out as the back release button is very easily engaged when handholding!