Hi Shannon! I totally understand! I sell art prints as well and this happens sometimes. But I agree with pillowsophi, you need to try everything you can to print this out and fulfill the order before refunding the money. I'm not sure if you print in house or through a printshop? I'm lucky to print in house, so whenever this happens, I can fiddle with the press until I've fixed the problem. But if you've tried cleaning out your press, and nothing is working, and you're on a time crunch, I suggest sending your art to an outside printshop. If the same problem occurs through their press, then you know it's the artwork and you should probably not relist the photo and offer to give the customer her money back or store credit with a discount. In addition, no matter the outcome, I would probably send her a handwritten note thanking her for understanding and patience and possibly a free gift inside the card or a gift certificate.
I hope that helps!
Heather
Pop Heart Press
www.popheartpress.blogspot.com