Banding on Images

Hi there - I recently purchased a 500EL - first couple of rolls were fine, but now each image is banding - please see example. The banding is definitely on the negative and not a scanning issue. Is this a light leak issue ?




Thanks,

Tim

Well the good news is that I dont think its the 'Blad - I've just developed a roll from my Fuji GSW690 and get the same effect - the bad news being I have no idea what I'm doing differently from normal ?