PIXMA PRO printers: paper feeding

When printing with the PIXMA PRO-10S or PRO-100S and using the rear tray for paper handling, you need to open the feed slot cover to adjust the paper guides for the paper size you are using. After you’ve adjusted the paper guides, be sure to close the feed slot cover again as if it is left open, paper cannot be fed and you will be unable to print.
PIXMA Pro printers