Well, the thing is my C35 works almost fine. I say almost because when flash unit is attached the camera still sets aperture and time adequate to what electric-eye sees (reflected light), while the meter needle in the viewfinder should show combination of shutter speed and aperture according to the flash GN, film ISO and distance to the object on which the lens is focused.
I dont't use original flash dedicated for C35 (X-14, X-20) as it's quite hard to find one. The one I use is Revue Tron SEL (similar size, a bit stronger - GN 21).
Any idea what the problem could be?