I have a C330 the shutter was sticking so I have had it apart cleaning it that part seems ok now. Seems to be ok with no flash.
I tried some flash shots inside I used a 40d hooked to a tv to get the the flash, iso, ap., and shutter speed set. That looked like I wanted so I set the C330 the same iso, ap, shutter, distance were all the same. Developed the hp5 in xtol and the film was blank. The numbers and lettering on the edges were there and two exposers had a little bit of image but not much.
I did notice afterwards the flash sync lever was about half way between the x and m.
Would that be enough to do it? I thought having the settings the same from both the 40d and the c330 it would be close.