Hi, I have recently purchased a Polaroid SX-70. The camera is in great condition and works fine except that almost systematically (12 out of 16 photos) I see small white streaks at the bottom of photo (see image). The streaks are not always exactly at the same place. This happened with Impossible SX-70 film and Impossible 600 with ND filter. I have cleaned the rollers with no result. Any suggestions are welcome, thanks!