Mamiya 645 light leak?

[earthmanbuck]

Hi folks, I recently got my first roll back from a Mamiya 645 I found on eBay. On a handful of the frames (4/15) there is a blue band in the top 3rd of the photo that looks like some kind of light leak or reflection. These tend to be in the lower light pictures...however, it's not in all the lower light pictures, and in one of them the light is pretty good.

I have a waist-level finder and a prism finder for this camera. The prism finder does have a line across the prism that would (I think) roughly line up with the colour band in these photos...however, to my recollection I was using the waist-level finder for most if not all of this roll. They were all shot with the same lens.

Any idea what this could be? I've included a picture where you can see the problem the best, as well as two very similar shots, taken one after the other, where it is in one but not the other.

 

[dxqcanada]

Probably need to replace light seals for the back: http://aki-asahi.com/store/html/Mamiya_M645/Foam/Mamiya_M645_seal.php

 

[earthmanbuck]

Thanks—might have to have a word with the guy who serviced it for me if that's the case.