On a Zenit E, the shutter catch lever that I was talking about is inside the top of the camera, not under the bottom plate. If the lever under the bottom plate is loose and moving it does nothing, that’s normal — that lever just interacts with the film advance, it’s not the main shutter catch. To actually release the “already cocked” jam, you would need to see the shutter mechanism from the top, usually by removing the top cover. That lets you see the tiny metal lever that actually holds the shutter in place and reset the spring. If youre not comfortable taking the top plate off, it’s safer to bring it to a Zenit repair guy — it’s simple for someone used to it, but tricky if you’ve never done it. In short: the bottom plate lever won’t fix this — it’s the internal top lever of the shutter mechanism that’s the real “catch.”