Hasselblad 503CW mirror getting stuck half-way, jamming the camera

[stevejack]

Hi All,

I have a Hasselblad 503CW which just jammed on me. I managed to re-cock the lens using the screw inside the camera body, and removed the lens, but now the body keeps jamming when I fire the shutter. 

With no lens and no film back mounted, I wind and cock the body just fine. The mirror comes down, it all looks and feels good. But when I press the shutter, the mirror starts to flip up but gets stuck part way. The rear flaps do not open and the body is jammed. If I manually push the mirror up with my finger, it then allows me to press the shutter button once again and the rear flaps will open and the camera can once again be wound and cocked. 

Does anyone have any ideas what might be the cause? I really appreciate any guidance here.