It's set up incorrectly.....your fold is too "tight"....experiment with your settings and you will fix it.......
I have actually moved the inside panel 1/8" away from the inside fold as that's what I thought it was originally. I have even moved the stock off centre so it hits the stop more square but to no avail. This is a great folder other than every now and again this niggling problem.
Is this a digital print? if it is let the paper season for couple days before you fold. might be a static issue.
Make the first fold a little longer. This will help with the spacing. You can run the folder at a high speed and not worry about any rabbit ears
