Hasselblad C-12 light leak

So as part of my Hasselblad "VPan" experiment, I got a C-12 and converted that look like this is light leak with the back. Sure enough, if I shine a light onto the gap, I could see light from the other side, unlike my othert good E12/A12 backs.

Are there other source of leaks besides the foam lining for the darkslide slot?