I recently acquired a nice Hasselblad 1600F with the 75mm Ektar. The problem is when winding it, the mirror flips down, which is normal, but at the end of the winding of each frame, the mirror flips back up and the shutter releases, without even my having touched the shutter release button. The shutter speeds seem accurate and the focal plane shutter curtains are not damaged. The small red/white window which indicates that the shutter is cocked or uncocked never turns red, indicating cocked. I guess that's why the shutter release button does nothing at all. Any ideas? Is this something that is a relatively easy fix? If not, who can you recommend to service a Hasselblad 1600F? Hasselblad no longer services these vintage cameras and my own repairman has no experience with focal plane Hasselblads. Thanks.