I purchased a Hasselblad 500 CM off Ebay. I`ve noticed that I get what looks like white streaks of various sizes in my photos. At first I thought it was flare, but the photos I took today seems to indicate a light leak.

I`ve attached one below.

I`ve done a bit of research on the web to see what is causing it, but there seems to be different reasons (loading the film incorrectly, damaged back, etc). I`m hoping it is not the lens (50mm F4 C Chrome). I`m wondering if someone here could shed some light on this for me. Thanks.