Polaroid 600 camera - dark stripes?

[primordialramen]

I've recently started using a Polaroid 600 camera, and I have a recurring problem with dark stripes showing up on my pictures.

For example: http://a7.sphotos.ak.fbcdn.net/hpho...445693228_682643227_11723721_1188796101_n.jpg

This doesn't occur in every picture I take, but I haven't worked out what is causing it. Any ideas?

Thanks in advance.

 

[ClassyLuke]

I'm kinda new to the world of photography, but I would try cleaning the rollers where the simi-developed picture comes through, it might help.