Epson Stylus Pro 4000 Reference Manual page 250

4. Pull the paper guide roller up, and slide the edge guide to the
left as far as it will go.
5. Clean the inside of the paper tray to remove any dust. Dust
may affect printout quality.
6. Thumb through a stack of paper, then tap it on a flat surface
to even the edges.
If your paper is curled, flatten it before you load it. If it curls
excessively and jams frequently, stop using it.
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Paper Handling